CN108690162B

CN108690162B - Methacrylic resin molded body, optical member, or automobile member

Info

Publication number: CN108690162B
Application number: CN201810264835.6A
Authority: CN
Inventors: 吉田淳一; 渡边春美; 多田裕
Original assignee: Asahi Kasei Corp
Current assignee: Asahi Kasei Corp
Priority date: 2017-04-07
Filing date: 2018-03-28
Publication date: 2020-11-27
Anticipated expiration: 2038-03-28
Also published as: CN108690162A; US20180291140A1; JP2018178095A; JP7025979B2

Abstract

The purpose of the present invention is to provide a methacrylic resin molded body which has high heat resistance, highly controlled birefringence, and excellent color tone and transparency. The methacrylic resin molded body is characterized by comprising a methacrylic resin or a composition containing the methacrylic resin, wherein the methacrylic resin comprises a structural unit (B) having a ring structure in a main chain, the structural unit (B) contains at least one structural unit selected from the group consisting of an N-substituted maleimide structural unit (B-1) and a lactone ring structural unit (B-2), the methacrylic resin has a glass transition temperature of more than 120 ℃ and 160 ℃ or less, the amount of a methanol-soluble component of the methacrylic resin is 5% by mass or less with respect to 100% by mass of the total amount of the methanol-insoluble component, and a Yellow Index (YI) measured by using an absorption cell having an optical path length of 10cm in a 20 w/v% chloroform solution of the methanol-insoluble component is 0to 7.

Description

Methacrylic resin molded body, optical member, or automobile member

Technical Field

The present invention relates to a methacrylic resin molded article having high heat resistance, highly controlled birefringence, and excellent color tone and transparency, and an optical member or an automobile member obtained from the molded article.

Background

In recent years, methacrylic resins have been drawing attention as various optical products because they are excellent in transparency, surface hardness, and the like, and also have small birefringence as optical characteristics, and for example, they are drawing attention as optical resins for optical materials such as flat panel displays such as liquid crystal displays, plasma displays, and organic EL displays, small infrared sensors, fine optical waveguides, micro lenses, pickup lenses for DVD/blu (blueraydik) that handles short-wavelength light, optical discs, optical films, plastic substrates, and the like, and the market thereof is expanding.

It is known that a methacrylic resin having a ring structure in its main chain and a composition containing the methacrylic resin have excellent performance in both heat resistance and optical characteristics (for example, see patent document 1), and the demand therefor has been rapidly expanding year by year. However, the methacrylic resin having a ring structure in its main chain after the heat resistance and optical characteristics are improved as described above may cause problems such as coloring or reduction in transmittance due to light absorption in a visible light region caused by the ring structure or the like. Therefore, a method for reducing the amount of unreacted cyclic monomer remaining in a methacrylic resin is disclosed in order to obtain a methacrylic resin having a ring structure in the main chain with less coloration and high transparency.

For example, patent document 2 discloses the following method: a process for producing a heat-resistant methacrylic resin which comprises using a monomer component comprising an N-substituted maleimide (a) and a methacrylate (b), supplying a part of the monomer component and then starting polymerization, and supplying the remaining part of the monomer component during polymerization, wherein the amount of the remaining N-substituted maleimide monomer is reduced by controlling the proportion of the N-substituted maleimide (a) in the unreacted monomer component present in the reaction system at the end of the supply of the monomer component to be smaller than the proportion of the N-substituted maleimide (a) in the total amount of the monomer component supplied, thereby obtaining a heat-resistant methacrylic resin having excellent transparency and less coloration.

Further, patent document 3 discloses the following method: in a polymerization system of a methacrylate monomer/maleimide monomer using a sulfur chain transfer agent such as thiol, an acidic substance is present in the reaction system, whereby residual maleimide monomer and maleimide monomer generated by heating during molding or the like are reduced, and coloring is reduced.

Documents of the prior art

Patent document

Patent document 1: international publication No. 2011/149088.

Patent document 2: japanese patent laid-open No. 9-324016.

Patent document 3: japanese patent laid-open No. 2001-233919.

Disclosure of Invention

However, in recent years, in order to expand the use of the methacrylic resin molded article from the optical film use to the use of a thick molded article such as a lens or a molded plate, it has been desired to provide a methacrylic resin molded article which is less colored and can exhibit high transparency even in a molded article having a long optical path length.

Patent documents 2 and 3 provide methods for reducing coloring by paying attention to N-substituted maleimide which is a monomer having strong coloring property, focusing on reduction in the amount of N-substituted maleimide remaining in a methacrylic resin and the amount of N-substituted maleimide generated by a thermal history such as molding processing, and reducing these methods.

However, as described above, for example, it is known that the improvement of the coloring degree and the transparency is insufficient as a methacrylic resin to be applied to a molded article having a long optical path length in a wide range of applications.

Therefore, it is strongly desired to further improve the coloring property and transparency of the methacrylic resin by focusing attention on the polymer itself, in addition to controlling the residual coloring monomer such as N-substituted maleimide.

The purpose of the present invention is to provide a methacrylic resin molded body which has high heat resistance, highly controlled birefringence, and excellent color tone and transparency.

The present inventors have made extensive studies to solve the above problems of the prior art, and as a result, they have found that the above problems can be solved by separating a methacrylic resin into a methanol-soluble component and a methanol-insoluble component and controlling the properties of each separated component, for example, in order to obtain a molded article having a long optical path length with less coloring and high transparency.

If improvement of the polymer itself is possible, the methacrylic resin having a ring structure in its main chain can be applied not only to a resin having a ring structure derived from an N-substituted maleimide monomer but also to a resin having a lactone ring structure unit, for example.

Namely, the present invention is as follows.

[1] A methacrylic resin molded body comprising a methacrylic resin or a composition containing the methacrylic resin,

the methacrylic resin comprises a structural unit (B) having a ring structure in the main chain, the structural unit (B) containing at least one structural unit selected from the group consisting of an N-substituted maleimide structural unit (B-1) and a lactone ring structural unit (B-2),

the glass transition temperature of the methacrylic resin is more than 120 ℃ and 160 ℃ or less,

the amount of the methanol-soluble component in the methacrylic resin is 5% by mass or less based on 100% by mass of the total amount of the methanol-soluble component and the methanol-insoluble component,

the Yellow Index (YI) of the methanol-insoluble component measured in a 20 w/v% chloroform solution using an absorption cell having an optical path length of 10cm is 0to 7.

[2] The molded methacrylic resin according to [1], wherein the transmittance at 680nm as measured by a 20 w/v% chloroform solution of the methanol-insoluble component using an absorption cell having an optical path length of 10cm is 90% or more.

[3] The molded methacrylic resin according to [1] or [2], wherein the methacrylic resin contains 50 to 97 mass% of a methacrylate monomer unit (A) when the amount of the methacrylic resin is 100 mass%.

[4] The methacrylic resin molded body according to any one of [1] to [3], wherein the methacrylic resin contains 3 to 30 mass% of a structural unit (B) having a ring structure in a main chain and 0to 20 mass% of another vinyl monomer unit (C) copolymerizable with a methacrylate ester monomer, based on 100 mass% of the methacrylic resin.

[5] The methacrylic resin molded body according to any one of [1] to [4], wherein the content of the structural unit (B) is 45 to 100% by mass when the total amount of the structural unit (B) and the monomer unit (C) is 100% by mass.

[6] The molded methacrylic resin according to [4] or [5], wherein the monomer unit (C) contains at least one structural unit selected from the group consisting of an acrylate monomer, an aromatic vinyl monomer and a vinyl cyanide monomer.

[7]Such as [1]]To [6]]The methacrylic resin molded body according to any one of the above, wherein the photoelastic coefficient of the methacrylic resin is-2X 10^-12～+2×10^-12Pa^-1。

[8] The molded methacrylic resin body according to any one of [1] to [7], wherein a ratio (Mz/Mw) of a Z-average molecular weight (Mz) to a weight-average molecular weight (Mw) measured by Gel Permeation Chromatography (GPC) on the methacrylic resin is 1.3 to 2.0.

[9] An optical member or an automotive member, characterized in that it is composed of the methacrylic resin molded body according to any one of [1] to [8 ].

According to the present invention, a methacrylic resin molded article having high heat resistance, highly controlled birefringence, and excellent color tone and transparency can be provided.

Detailed Description

Hereinafter, an embodiment of the present invention (hereinafter, referred to as "the present embodiment") will be described in detail, but the present invention is not limited to the following, and can be carried out by being variously modified within the scope of the gist thereof.

(methacrylic resin molded article)

The methacrylic resin molded article of the present embodiment is composed of a methacrylic resin or a composition containing the methacrylic resin, the methacrylic resin comprises a structural unit (B) having a ring structure in the main chain, the structural unit (B) comprising at least one structural unit selected from the group consisting of an N-substituted maleimide structural unit (B-1) and a lactone ring structural unit (B-2), the methacrylic resin has a glass transition temperature of more than 120 ℃ and 160 ℃ or less, the amount of the methanol-soluble component of the methacrylic resin is 5% by mass or less relative to 100% by mass of the total amount of the methanol-soluble component and the amount of the methanol-insoluble component, and the Yellowness Index (YI) of the methacrylic resin is 0to 7 as measured on a 20 w/v% chloroform solution of the methanol-insoluble component using an absorption cell having an optical path length of 10 cm.

(methacrylic resin)

The methacrylic resin constituting the methacrylic resin molded article of the present embodiment contains a methacrylic acid ester monomer unit (a) and a structural unit (B) having a ring structure in the main chain, and optionally contains another vinyl monomer unit (C) copolymerizable with the methacrylic acid ester monomer, and the structural unit (B) is at least one selected from the group consisting of a structural unit (B-1) derived from an N-substituted maleimide monomer and a lactone ring structure unit (B-2).

Hereinafter, each monomer structural unit will be described.

Structural units (A) from methacrylate monomers

First, the structural unit (a) derived from a methacrylate monomer will be described.

The structural unit (a) derived from a methacrylate monomer is formed from a monomer selected from the following methacrylate group, for example.

Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, cyclooctyl methacrylate, tricyclodecyl methacrylate, bicyclooctyl methacrylate, tricyclodecyl methacrylate, isobornyl methacrylate, phenyl methacrylate, benzyl methacrylate, 1-phenylethyl methacrylate, 2-phenoxyethyl methacrylate, 3-phenylpropyl methacrylate, and 2, 4, 6-tribromophenyl methacrylate.

These monomers are sometimes used alone, and two or more of them are sometimes used in combination.

Among the above-mentioned methacrylic acid esters, methyl methacrylate and benzyl methacrylate are preferable in terms of excellent transparency and weather resistance of the obtained methacrylic resin.

The monomer (a) may contain only one kind of the structural unit (a) derived from a methacrylate monomer, or may contain two or more kinds.

From the viewpoint of sufficiently imparting heat resistance to a methacrylic resin by a structural unit (B) having a ring structure in the main chain described later, the content of the structural unit (a) derived from a methacrylate ester monomer is preferably 50 to 97% by mass, more preferably 55 to 97% by mass, even more preferably 55 to 95% by mass, even more preferably 60 to 93% by mass, and particularly preferably 60 to 90% by mass, based on 100% by mass of the methacrylic resin.

Hereinafter, the structural unit (B) having a ring structure in its main chain will be described.

Structural units (B-1) derived from N-substituted maleimide monomers

Next, the structural unit (B-1) derived from the N-substituted maleimide monomer will be described.

The structural unit (B-1) derived from the N-substituted maleimide monomer may be at least one selected from the group consisting of a monomer represented by the following formula (1) and/or a monomer represented by the following formula (2), and is preferably formed from both the monomers represented by the following formulae (1) and (2).

In the formula (1), R¹R represents any of an aralkyl group having 7 to 14 carbon atoms and an aryl group having 6 to 14 carbon atoms²And R³Each independently represents any group of a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, and an aryl group having 6 to 14 carbon atoms.

In addition, when R is²When it is aryl, R²May contain a halogen as a substituent.

In addition, R¹May be substituted by halogen atomsAlkyl group having 1 to 6 carbon atoms, alkoxy group having 1 to 6 carbon atoms, nitro group, benzyl group and the like.

In the formula (2), R⁴R represents any of a hydrogen atom, a cycloalkyl group having 3 to 12 carbon atoms and an alkyl group having 1 to 12 carbon atoms⁵And R⁶Each independently represents any group of a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, and an aryl group having 6 to 14 carbon atoms.

Specific examples are shown below.

Examples of the monomer represented by the formula (1) include N-phenylmaleimide, N-benzylmaleimide, N- (2-chlorophenyl) maleimide, N- (4-bromophenyl) maleimide, N- (2-methylphenyl) maleimide, N- (2-ethylphenyl) maleimide, N- (2-methoxyphenyl) maleimide, N- (2-nitrophenyl) maleimide, N- (2, 4, 6-trimethylphenyl) maleimide, N- (4-benzylphenyl) maleimide, N- (2, 4, 6-tribromophenyl) maleimide, N-naphthylmaleimide, N-benzylmaleimide, N-phenylmaleimide, N- (2-methoxyphenyl) maleimide, N- (4-bromophenyl) maleimide, N-naphthylmaleimide, N- (2-bromophenyl) maleimide, N- (, N-anthrylmaleimide, 3-methyl-1-phenyl-1H-pyrrole-2, 5-dione, 3, 4-dimethyl-1-phenyl-1H-pyrrole-2, 5-dione, 1, 3-diphenyl-1H-pyrrole-2, 5-dione, 1, 3, 4-triphenyl-1H-pyrrole-2, 5-dione, and the like.

Among the monomers, N-phenylmaleimide and N-benzylmaleimide are preferable from the viewpoint of excellent heat resistance and optical properties such as birefringence of the obtained methacrylic resin.

These monomers may be used alone or in combination of two or more.

Examples of the monomer represented by the formula (2) include N-methylmaleimide, N-ethylmaleimide, N-N-propylmaleimide, N-isopropylmaleimide, N-N-butylmaleimide, N-isobutylmaleimide, N-sec-butylmaleimide, N-tert-butylmaleimide, N-N-pentylmaleimide, N-N-hexylmaleimide, N-N-heptylmaleimide, N-N-octylmaleimide, N-laurylmaleimide, N-stearylmaleimide, N-cyclopentylmaleimide, N-cyclohexylmaleimide, 1-cyclohexyl-3-methyl-1-phenyl-1H-pyrrole-2, 5-dione, 1-cyclohexyl-3, 4-dimethyl-1-phenyl-1H-pyrrole-2, 5-dione, 1-cyclohexyl-3, 4-diphenyl-1H-pyrrole-2, 5-dione, and the like.

Among the above monomers, N-methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide and N-cyclohexylmaleimide are preferable from the viewpoint of excellent weather resistance of methacrylic resins, and N-cyclohexylmaleimide is particularly preferable from the viewpoint of excellent low hygroscopicity which has been required for optical materials in recent years.

These monomers can be used alone or in combination of two or more.

In the methacrylic resin constituting the methacrylic resin molded body of the present embodiment, it is particularly preferable to use the monomer represented by the formula (1) in combination with the monomer represented by the formula (2) in order to develop highly controlled birefringence characteristics.

The molar ratio (B1/B2) of the content (B1) of the structural unit derived from the monomer represented by the formula (1) to the content (B2) of the structural unit derived from the monomer represented by the formula (2) is preferably greater than 0 and 15 or less, more preferably greater than 0 and 10 or less.

When the molar ratio B1/B2 is within the above range, the methacrylic resin molded article of the present embodiment exhibits good heat resistance and good photoelastic characteristics without yellowing while maintaining transparency and without impairing environmental resistance.

The content of the structural unit (B-1) derived from the N-substituted maleimide monomer is not particularly limited as long as the obtained composition satisfies the glass transition temperature range of the present embodiment, and is preferably 5 to 40 mass%, more preferably 5 to 35 mass% based on 100 mass% of the methacrylic resin.

When the content is within the above range, a more sufficient effect of improving heat resistance is obtained for the methacrylic resin molded article, and a more preferable effect of improving weather resistance, low water absorption and optical characteristics is obtained. In order to prevent the decrease in physical properties of the methacrylic resin molded product due to the decrease in reactivity of the monomer component during the polymerization reaction and the increase in the amount of the monomer remaining without reaction, it is effective to set the content of the structural unit derived from the N-substituted maleimide monomer to 40 mass% or less.

Lactone ring structure unit (B-2)

Methacrylic resins having a lactone ring structure unit in the main chain can be formed by the methods described in, for example, japanese patent laid-open nos. 2001-151814, 2004-168882, 2005-146084, 2006-96960, 2006-171464, 2007-63541, 2007-297620, and 2010-180305.

The methacrylic resin constitutes the methacrylic resin molded body of the present embodiment, and the lactone ring structure unit constituting the methacrylic resin may be formed after polymerization of the resin.

The lactone ring structure unit in the present embodiment is preferably a six-membered ring in view of excellent stability of the ring structure.

The lactone ring structure unit having a six-membered ring is particularly preferably a structure represented by the following general formula (3), for example.

In the above general formula (3), R¹⁰、R¹¹And R¹²Independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms.

Examples of the organic residue include the following groups: saturated aliphatic hydrocarbon groups having 1 to 20 carbon atoms (such as alkyl groups) such as methyl, ethyl and propyl groups; an unsaturated aliphatic hydrocarbon group (e.g., alkenyl group) having 2 to 20 carbon atoms such as an ethylene group and an allyl group; an aromatic hydrocarbon group (e.g., aryl group) having 6 to 20 carbon atoms such as phenyl group and naphthyl group; and a group in which one or more hydrogen atoms in the saturated aliphatic hydrocarbon group, the unsaturated aliphatic hydrocarbon group, and the aromatic hydrocarbon group are substituted with at least one group selected from the group consisting of a hydroxyl group, a carboxyl group, an ether group, and an ester group.

The lactone ring structure can be formed, for example, by copolymerizing an acrylic monomer having a hydroxyl group with a methacrylate monomer such as methyl methacrylate, introducing a hydroxyl group, an ester group, or a carboxyl group into the molecular chain, and then subjecting the hydroxyl group and the ester group, or the hydroxyl group and the carboxyl group to dealcoholization (esterification) or dehydration condensation (hereinafter, also referred to as "cyclized condensation reaction").

Examples of the acrylic monomer having a hydroxyl group used in polymerization include 2- (hydroxymethyl) acrylic acid, 2- (hydroxyethyl) acrylic acid, and alkyl 2- (hydroxymethyl) acrylates (for example, methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, n-butyl 2- (hydroxymethyl) acrylate, tert-butyl 2- (hydroxymethyl) acrylate), alkyl 2- (hydroxyethyl) acrylate; preferably, 2- (hydroxymethyl) acrylic acid, alkyl 2- (hydroxymethyl) acrylate as a monomer having a hydroxyallyl site; particularly preferred are methyl 2- (hydroxymethyl) acrylate and ethyl 2- (hydroxymethyl) acrylate.

The content of the lactone ring structure unit in the methacrylic resin having a lactone ring structure unit in the main chain is not particularly limited as long as it satisfies the range of the glass transition temperature of the methacrylic resin of the present embodiment, but is preferably 5 to 40% by mass, more preferably 5 to 35% by mass, based on 100% by mass of the methacrylic resin.

When the content of the lactone ring structural unit is within the above range, the ring structure introducing effect such as improvement of solvent resistance and improvement of surface hardness can be exhibited while maintaining moldability.

The content of the lactone ring structure in the methacrylic resin can be determined by the method described in the above patent document.

From the viewpoint of heat resistance, thermal stability, strength, and fluidity of the methacrylic resin constituting the methacrylic resin molded product of the present embodiment, the content of the structural unit (B) having a ring structure in the main chain is preferably 3 to 40% by mass, the lower limit is more preferably 5% by mass or more, further preferably 7% by mass or more, further more preferably 8% by mass or more, the upper limit is more preferably 30% by mass or less, further preferably 28% by mass or less, further more preferably 25% by mass or less, particularly preferably 20% by mass or less, particularly preferably 18% by mass or less, and most preferably less than 15% by mass, based on 100% by mass of the methacrylic resin.

Other vinyl monomer units (C) copolymerizable with the methacrylate ester monomer

The methacrylic resin constitutes the methacrylic resin molded article of the present embodiment, and examples of the other vinyl monomer unit (C) (hereinafter, sometimes referred to as "C monomer unit") copolymerizable with a methacrylic acid ester monomer, which can constitute the methacrylic resin, include an aromatic vinyl monomer unit (C-1), an acrylic acid ester monomer unit (C-2), a vinyl cyanide monomer unit (C-3), and the other monomer unit (C-4).

The other vinyl monomer unit (C) copolymerizable with the methacrylate ester monomer may be used alone or in combination of two or more.

The monomer unit (C) can be suitably selected from materials according to the properties required for the methacrylic resin constituting the methacrylic resin molded article of the present embodiment, but when properties such as thermal stability, flowability, mechanical properties, and chemical resistance are particularly required, at least one selected from the group consisting of an aromatic vinyl monomer unit (C-1), an acrylate monomer unit (C-2), and a vinyl cyanide monomer unit (C-3) is preferable.

[ aromatic vinyl monomer Unit (C-1) ]

The methacrylic resin molded product of the present embodiment is composed of a methacrylic resin, the methacrylic resin is composed of an aromatic vinyl monomer unit (C-1), and the monomer constituting the aromatic vinyl monomer unit (C-1) is not particularly limited, but an aromatic vinyl monomer represented by the following general formula (4) is preferable.

In the above general formula (4), R¹Represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and the alkyl group may be substituted with, for example, a hydroxyl group.

R²Is an arbitrary group selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 6 to 8 carbon atoms and an aryloxy group having 6 to 8 carbon atoms, R²These groups may be all the same or different. In addition, R²May also form ring structures with each other.

n represents an integer of 0to 5.

Specific examples of the monomer represented by the above general formula (4) are not particularly limited, examples thereof include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2, 4-dimethylstyrene, 2, 5-dimethylstyrene, 3, 4-dimethylstyrene, 3, 5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, p-tert-butylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 1-diphenylethylene, isopropenylbenzene (. alpha. -methylstyrene), isopropenyltoluene, isopropenylethylbenzene, isopropenylpropylbenzene, isopropenylbutylbenzene, isopropenylpentylbenzene, isopropenylhexylbenzene, isopropenyloctylbenzene,. alpha. -hydroxymethylstyrene and. alpha. -hydroxyethylstyrene.

Among the above, styrene and isopropenylbenzene are preferable, and styrene is more preferable from the viewpoint of imparting fluidity, improving polymerization conversion, reducing unreacted monomers, and the like.

In the methacrylic resin of the present embodiment, the above-mentioned substances can be appropriately selected in accordance with the required properties.

In consideration of the balance among heat resistance, reduction in the number of residual monomers, and fluidity, the content of the aromatic vinyl monomer unit (C-1) is preferably 23% by mass or less, more preferably 20% by mass or less, further preferably 18% by mass or less, further more preferably 15% by mass or less, and still further preferably 10% by mass or less, based on 100% by mass of the total amount of the monomer unit (a) and the structural unit (B).

When the aromatic vinyl monomer unit (C-1) is used in combination with the maleimide structural unit (B-1), the ratio (mass ratio) of the content of the (C-1) monomer unit to the content of the (B-1) structural unit (i.e., the (C-1) content/(B-1) content) is preferably 0.3 to 5 from the viewpoints of processing flowability during film formation, and the effect of reducing silver streaks (silver streaks) by reducing residual monomers.

Here, from the viewpoint of maintaining good color tone and heat resistance, the upper limit value is preferably 5 or less, more preferably 3 or less, and still more preferably 1 or less. From the viewpoint of reducing the residual monomer, the lower limit value is preferably 0.3 or more, and more preferably 0.4 or more.

The aromatic vinyl monomer (C-1) may be used alone or in combination of two or more.

[ acrylic acid ester monomer Unit (C-2) ]

The methacrylic resin constitutes the methacrylic resin molded body of the present embodiment, the acrylic ester monomer unit (C-2) constitutes the methacrylic resin, and the monomer constituting the acrylic ester monomer unit (C-2) is not particularly limited, but an acrylic ester monomer represented by the following general formula (5) is preferable.

In the above general formula (5), R¹R represents a hydrogen atom or an alkoxy group having 1 to 12 carbon atoms²Represents any group of alkyl group having 1 to 18 carbon atoms, cycloalkyl group having 3 to 12 carbon atoms, and aryl group having 6 to 14 carbon atoms.

In the methacrylic resin for a film of the present embodiment, from the viewpoint of improving weather resistance, heat resistance, fluidity, and thermal stability, the monomer for forming the acrylic ester monomer unit (C-2) is preferably methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, or the like, more preferably methyl acrylate, ethyl acrylate, and n-butyl acrylate, and from the viewpoint of easiness of obtaining, methyl acrylate and ethyl acrylate are further preferable.

The acrylate monomer unit (C-2) may be used alone or in combination of two or more.

From the viewpoint of heat resistance and thermal stability, the content of the acrylate monomer unit (C-2) is preferably 5% by mass or less, more preferably 3% by mass or less, based on 100% by mass of the total amount of the monomer unit (a) and the structural unit (B).

[ vinyl cyanide-based monomer Unit (C-3) ]

The methacrylic resin constitutes the methacrylic resin molded body of the present embodiment, the vinyl cyanide monomer unit (C-3) constitutes the methacrylic resin, and the monomer constituting the vinyl cyanide monomer unit (C-3) is not particularly limited, but examples thereof include acrylonitrile, methacrylonitrile, ethacrylonitrile, vinylidene cyanide and the like, and among them, acrylonitrile is preferable from the viewpoint of easiness of obtaining and imparting chemical resistance.

The vinyl cyanide-based monomer unit (C-3) may be used alone or in combination of two or more.

From the viewpoint of maintaining solvent resistance and heat resistance, the content of the vinyl cyanide-based monomer unit (C-3) is preferably 15% by mass or less, more preferably 12% by mass or less, and still more preferably 10% by mass or less, based on 100% by mass of the total amount of the monomer unit (a) and the structural unit (B).

[ (C-1) to (C-3) monomer units (C-4) ]

The methacrylic resin constitutes the methacrylic resin molded article of the present embodiment, the monomer unit (C-4) other than (C-1) to (C-3) constitutes the methacrylic resin, and the monomer constituting the monomer unit (C-4) other than (C-1) to (C-3) is not particularly limited, and examples thereof include amides such as acrylamide and methacrylamide; glycidyl compounds such as glycidyl (meth) acrylate and allyl glycidyl ether; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid, and half-esters and anhydrides thereof; unsaturated alcohols such as methallyl alcohol and allyl alcohol; olefins such as ethylene, propylene and 4-methyl-1-pentene; vinyl compounds and vinylidene compounds other than those described above, such as vinyl acetate, 2-hydroxymethyl-1-butene, methyl ketene, N-vinylpyrrolidone and N-vinylcarbazole.

Further, examples of the crosslinkable compound having a plurality of reactive double bonds include esters obtained by esterifying both terminal hydroxyl groups of ethylene glycol or its oligomer with acrylic acid or methacrylic acid, such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and tetraethylene glycol di (meth) acrylate; esters obtained by esterifying the hydroxyl groups of two alcohols with acrylic acid or methacrylic acid, such as neopentyl glycol di (meth) acrylate and di (meth) acrylate; esters obtained by esterifying polyvalent alcohol derivatives such as trimethylolpropane and pentaerythritol with acrylic acid or methacrylic acid; multifunctional monomers such as divinylbenzene, and the like.

From the viewpoint of ease of acquisition, among the monomers constituting the monomer unit (C), at least one selected from the group consisting of methyl acrylate, ethyl acrylate, styrene, and acrylonitrile is preferable.

From the viewpoint of enhancing the effect of imparting heat resistance by the structural unit (B), the content of the other vinyl monomer unit (C) copolymerizable with the methacrylate ester monomer is 0to 20% by mass, preferably 0to 18% by mass, and more preferably 0to 15% by mass, based on 100% by mass of the methacrylic resin.

In particular, when a crosslinkable polyfunctional (meth) acrylate having a plurality of reactive double bonds is used as the (C) monomer unit, the content of the (C) monomer unit is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and further preferably 0.2% by mass or less from the viewpoint of the fluidity of the polymer.

In particular, in the present embodiment, from the viewpoint of heat resistance and optical properties of the methacrylic resin molded product, the content of the (B) structural unit is 45 to 100% by mass when the total amount of the (B) structural unit and the (C) monomer unit is 100% by mass. In this case, the content of the structural unit (C) is 0to 55% by mass. The content of the structural unit (B) is preferably 50 to 100% by mass, more preferably 50 to 90% by mass, and still more preferably 50 to 80% by mass.

Next, the characteristics of the methacrylic resin constituting the methacrylic resin molded product of the present embodiment will be described.

The glass transition temperature (Tg) of the methacrylic resin constituting the methacrylic resin molded article of the present embodiment is greater than 120 ℃ and 160 ℃ or less.

When the glass transition temperature of the methacrylic resin is more than 120 ℃, sufficient heat resistance required for optical members such as recent lens molded articles, automobile members such as in-vehicle displays, and film molded article optical films for liquid crystal displays can be more easily obtained. From the viewpoint of dimensional stability at the use environment temperature, the glass transition temperature (Tg) is more preferably 125 ℃ or higher, and still more preferably 130 ℃ or higher.

On the other hand, when the glass transition temperature (Tg) of the methacrylic resin is 160 ℃ or lower, melt processing under extremely high temperature conditions can be avoided, thermal decomposition of the resin and the like can be suppressed, and a good product can be obtained. For the above reasons, the glass transition temperature (Tg) is preferably 150 ℃ or lower.

The glass transition temperature (Tg) can be determined by measurement according to JIS-K7121. Specifically, the measurement can be performed by the method described in the examples below.

The ratio of the amount of the methanol-soluble component to the total 100 mass% of the amount of the methanol-soluble component and the amount of the methanol-insoluble component in the methacrylic resin molded article of the present embodiment is greater than 0 mass% and 5 mass% or less, preferably 0.1 mass% or more and 4.5 mass% or less, more preferably 0.1 mass% or more and 4 mass% or less, still more preferably 0.1 mass% or more and 3.5 mass% or less, preferably 0.2 mass% or more and 3 mass% or less, and still more preferably 0.3 mass% or more and 2.5 mass% or less.

By setting the amount of the soluble component to 5 mass% or less, troubles during molding such as contamination of a casting roll during film molding and occurrence of silver streaks during injection molding can be suppressed, and the color tone of the molded article can be improved.

The methanol-soluble component and the methanol-insoluble component are those obtained by preparing a chloroform solution of a methacrylic resin, then adding the solution dropwise to methanol to reprecipitate, separating the filtrate and the filtrate, and then drying the separated products, and specifically can be obtained by the method described in the following examples.

The methanol-soluble components include: monomers remaining without being completely reacted in the polymerization step, oligomers or low molecular weight components having a molecular weight of about several hundred to several thousand produced in the polymerization step, monomers, oligomers, low molecular weight components produced in the thermal decomposition in the devolatilization step, and the like. It is considered that a failure at the time of molding can be suppressed by reducing a component having a relatively low molecular weight which is liable to migrate to the surface of a molded article. Further, the color tone of the molded article can be improved by reducing low molecular weight components that readily absorb visible light in a low wavelength region having a wavelength of 500nm or less.

The methacrylic resin constituting the methacrylic resin molded article of the present embodiment has a Yellowness Index (YI) of 0to 7, preferably 0.5 to 6, more preferably 0.8 to 5, and further preferably 1 to 4, as measured with a 20 w/v% chloroform solution of a methanol-insoluble component using an absorption cell having an optical path length of 10 cm.

The methacrylic resin constituting the methacrylic resin molded product of the present embodiment preferably has a transmittance of 90% or more, more preferably 91% or more, and even more preferably 92% or more, at 680nm as measured under the same conditions as the conditions for measuring YI.

By setting the Yellowness Index (YI) and the transmittance within the above ranges, a molded article preferable for optical use can be obtained.

The Yellowness Index (YI) and transmittance can be measured by the methods described in the examples below.

As a factor of lowering the light transmittance of the molded article, light scattering due to foreign matter such as gel or a copolymer component having a non-uniform refractive index is presumed. Since these components are incorporated in the methanol-insoluble component, it is considered that if the light transmittance of the methanol-insoluble component represented by a wavelength of 680nm is high, a molded article having high light transmittance can be obtained. Further, if the YI of the methanol-insoluble component is low, that is, the wavelength dependence of the light transmittance is small, a molded article having a high light transmittance and a good color tone can be obtained.

The methacrylic resin constituting the methacrylic resin molded article of the present embodiment has a weight average molecular weight (Mw) as measured by Gel Permeation Chromatography (GPC) in terms of polymethyl methacrylate, preferably in the range of 65000 to 300000, more preferably in the range of 100000 to 220000, and still more preferably in the range of 120000 to 180000.

When the weight average molecular weight (Mw) is within the above range, the balance of mechanical strength and fluidity is also excellent.

In the methacrylic resin of the present embodiment, regarding the ratio among the Z-average molecular weight (Mz), the weight average molecular weight (Mw), and the number average molecular weight (Mn) as parameters representing the molecular weight distribution, when considering the balance between the flowability and the mechanical strength, the Mw/Mn is preferably 1.5 to 3.0, more preferably 1.6 to 2.5, and further preferably 1.6 to 2.3; Mz/Mw is preferably 1.3 to 2.0, more preferably 1.3 to 1.8, and further preferably 1.4 to 1.7.

In particular, when Mz/Mw is in the above range, a methacrylic resin having an excellent color tone can be produced.

The Z-average molecular weight, the weight-average molecular weight, and the number-average molecular weight of the methacrylic resin can be measured by the methods described in the examples below.

The methacrylic resin molded body of the present embodiment is constituted by a methacrylic resin containing a structural unit (X) having a ring structure in its main chain and having a photoelastic coefficient C_RIs preferably 3.0X 10^-12Pa^-1Hereinafter, more preferably 2.0 × 10^-12Pa^-1Hereinafter, more preferably 1.0 × 10^-12Pa^-1The following.

Regarding the photoelastic coefficient, various documents are described (for example, refer to "general chemical introduction, No.39, 1998 (published by academic society) (chemical Gross, No.39, 1998 (published by academic society センター))), and are defined by the following formulae (i-a) and (i-b). Coefficient of photoelasticity C_RThe closer to zero the value of (b) is, the smaller the birefringence change caused by the external force is.

C_R＝|Δn|/σ_R (i-a)

|Δn|＝nx-ny (i-b)

(wherein, respectively, C_RDenotes the photoelastic coefficient, σ_RRepresents a tensile stress, | Δ n | represents an absolute value of birefringence, nx represents a refractive index in a stretching direction, ny represents a refractive index in a direction perpendicular to the stretching direction in a plane)

If the photoelastic coefficient C of the methacrylic resin of the present embodiment_RHas an absolute value of 3.0X 10^-12Pa^-1Hereinafter, even when the film is formed into a film and used in a liquid crystal display device, the occurrence of phase difference unevenness, a decrease in contrast in the peripheral portion of a display screen, or the occurrence of light leakage can be suppressed or prevented.

Photoelastic coefficient C for methacrylic resin_RSpecifically, it can be determined by the method described in the following examples.

(method for producing methacrylic resin)

Hereinafter, a method for producing a methacrylic resin constituting the methacrylic resin molded product of the present embodiment will be described.

The method for producing a methacrylic resin constituting the methacrylic resin molded product of the present embodiment includes the following production methods of the first and second embodiments.

In a first aspect, two or more monomers including a methacrylate monomer are radically polymerized in a solvent in a batch or semi-batch manner, and in this method, a radical polymerization initiator having a half-life of 1 minute or more and less than 60 minutes under a polymerization temperature condition is used as the radical polymerization initiator, and the radical polymerization initiator is added to a reactor while gradually decreasing the amount of the radical polymerization initiator added per unit time to carry out polymerization of the monomers, and the amount of the radical polymerization initiator added after the time when the polymerization conversion rate reaches 85% is set to 10to 25% by mass when the total amount of the radical polymerization initiator added is 100% by mass.

In the first embodiment, the radical polymerization initiator may be added continuously or intermittently, and in the case of intermittent addition, the amount of addition per unit time is not considered for the time during which the addition is not performed.

In a second aspect, two or more monomer components including a methacrylate ester monomer are radically polymerized in a solvent in a batch or semi-batch manner, and in this method, a radical polymerization initiator having a half-life of 60 minutes or more under a polymerization temperature condition is used as the radical polymerization initiator, 25 mass% or more of the total amount of the radical polymerization initiator is added within 30 minutes from the start of addition of the polymerization initiator, and 25 mass% or more of the total amount of the monomer is added 30 minutes after the start of addition of the polymerization initiator.

In the polymerization, when the temperature varied during the polymerization, the time average value of the polymerization temperature until the polymerization conversion rate reached 95% was regarded as the polymerization temperature.

Hereinafter, a method for producing a methacrylic resin containing an N-substituted maleimide-based structural unit (B-1) having a ring structure as the main chain as the structural unit (B) will be described in detail.

As a method for producing a methacrylic resin having a structural unit (B-1) derived from an N-substituted maleimide monomer in the main chain, which constitutes the methacrylic resin molded article of the present embodiment, a solution polymerization method is used.

In the production method in the present embodiment, a batch (batch) method or a semi-batch (semi-batch) method can be used as a polymerization method. Here, the batch type means a process of charging the raw materials in total amount into the reactor, starting and proceeding the reaction, and recovering the product after completion, and the semi-batch type means a process of simultaneously charging the raw materials or recovering the product while the reaction is proceeding. In the method for producing a methacrylic resin having a structural unit derived from an N-substituted maleimide monomer in the main chain according to the present embodiment, a semi-batch method is preferable in which a part of the raw materials is charged after the reaction is started.

In the method for producing a methacrylic resin constituting the methacrylic resin molded body of the present embodiment, polymerization of a monomer by radical polymerization is used.

The polymerization solvent to be used is not particularly limited as long as it is a polymerization solvent capable of appropriately maintaining the viscosity of the reaction solution for the purpose of enhancing the solubility of the maleimide-based copolymer obtained by polymerization, preventing gelation, or the like.

Specific examples of the polymerization solvent include aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and cumene; ketones such as methyl isobutyl ketone, butyl cellosolve, methyl ethyl ketone, and cyclohexanone; polar solvents such as dimethylformamide and 2-methylpyrrolidone.

In addition, an alcohol such as methanol, ethanol, or isopropyl alcohol may be used in combination as a polymerization solvent within a range not inhibiting the dissolution of the polymerization product at the time of polymerization.

The amount of the solvent used in the polymerization is not particularly limited as long as the solvent can be easily removed without causing precipitation of a copolymer or a monomer used in the production by the polymerization, but is preferably 10to 200 parts by mass, for example, based on 100 parts by mass of the total amount of the monomers to be blended. More preferably 25 to 200 parts by mass, still more preferably 50 to 200 parts by mass, and still more preferably 50 to 150 parts by mass.

The polymerization temperature is not particularly limited as long as the polymerization is carried out, but is preferably 70 to 180 ℃ and more preferably 80 to 160 ℃. More preferably 90to 150 ℃ and still more preferably 100 to 150 ℃. From the viewpoint of productivity, it is preferably 70 ℃ or higher, and in order to suppress side reactions during polymerization and obtain a polymer having a desired molecular weight and quality, it is preferably 180 ℃ or lower.

The polymerization time is not particularly limited as long as it is a time that can obtain a necessary degree of polymerization at a necessary conversion rate, and is preferably 2 to 15 hours, more preferably 3 to 12 hours, and further preferably 4 to 10 hours from the viewpoint of productivity and the like.

The methacrylic resin having a structural unit derived from an N-substituted maleimide monomer in the main chain constituting the methacrylic resin molded product of the present embodiment preferably has a polymerization conversion rate of 93 to 99.9%, more preferably 95 to 99.5%, and further preferably 97 to 99% at the end of polymerization.

The polymerization conversion rate is a ratio of a value obtained by subtracting the total mass of the monomers remaining at the end of polymerization from the total mass of the monomers added to the polymerization system to the total mass of the monomers added to the polymerization system.

The amount of the N-substituted maleimide monomer remaining in the solution after polymerization (N-substituted maleimide remaining amount) is preferably 100 to 7000 mass ppm or less, more preferably 200 to 5000 mass ppm or less, and still more preferably 300to 3000 mass ppm or less.

Although the higher the polymerization conversion and the smaller the amount of the N-substituted maleimide remaining, the less the amount of the monomer to be recycled in the solvent recovery system, the less the load on the purification system and the higher the unit cost ( th site) are, and it is economical, the more the polymerization conversion is increased and the more the amount of the N-substituted maleimide remaining is decreased, the more the amount of the low-molecular-weight coloring component and the amount of the methanol-soluble component increase, and the color tone and the moldability may be adversely affected.

In the polymerization reaction, a chain transfer agent may be added as necessary to carry out the polymerization.

As the chain transfer agent, chain transfer agents used in general radical polymerization can be used, and the following are mentioned, for example: thiol compounds such as n-butyl mercaptan, n-octyl mercaptan, n-decyl mercaptan, n-dodecyl mercaptan, and 2-ethylhexyl thioglycolate (2-ethylhexyl thioglycolate); halogen compounds such as carbon tetrachloride, methylene chloride and bromoform; unsaturated hydrocarbon compounds such as α -methylstyrene dimer, α -terpinene, dipentene, terpinolene, and the like.

The chain transfer agent may be used alone or in combination of two or more.

The chain transfer agent may be added at any stage as long as the polymerization reaction is in progress, and is not particularly limited.

The amount of the chain transfer agent to be added may be 0.01 to 1 part by mass, preferably 0.05 to 0.5 part by mass, based on 100 parts by mass of the total amount of the monomers to be polymerized.

In the solution polymerization, it is important to reduce the dissolved oxygen concentration in the polymerization solution as much as possible in advance, and for example, the dissolved oxygen concentration is preferably 10ppm or less.

The concentration of dissolved oxygen can be measured using, for example, a dissolved oxygen METER DO METER B-505 (manufactured by Kaisha electronic industries, Ltd.). As a method for reducing the dissolved oxygen concentration, the following method can be suitably selected: a method of bubbling an inert gas into a polymerization solution, a method of repeating an operation of pressurizing a vessel containing a polymerization solution with an inert gas to about 0.2MPa and then depressurizing the vessel before polymerization, a method of circulating an inert gas through a vessel containing a polymerization solution, and the like.

At the time of polymerization, a polymerization initiator is added.

As the polymerization initiator, any initiator generally used in radical polymerization can be used, and examples thereof include organic peroxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butyl peroxyisopropylcarbonate, t-amyl peroxy-2-ethylhexanoate, t-amyl peroxyisononanoate, and 1, 1-di-t-butyl peroxycyclohexane; azo compounds such as 2,2 '-azobis (isobutyronitrile), 1' -azobis (cyclohexanecarbonitrile), 2 '-azobis (2, 4-dimethylvaleronitrile), and dimethyl 2, 2' -azobisisobutyrate.

These polymerization initiators may be used alone or in combination of two or more.

The above polymerization initiator may be added at any stage as long as the polymerization reaction is in progress.

The amount of the polymerization initiator added may be 0.01 to 1 part by mass, preferably 0.05 to 0.5 part by mass, based on 100 parts by mass of the total amount of the monomers used for polymerization.

In the polymerization of a methacrylic resin having a cyclic structure unit derived from an N-substituted maleimide monomer, which constitutes the methacrylic resin molded article of the present embodiment, a methacrylic resin can be produced by controlling the concentrations of each comonomer and a radical having polymerization activity present in the reaction system, wherein the amount of a methanol-soluble component is 5% by mass or less relative to 100% by mass of the total amount of the methanol-soluble component and the amount of a methanol-insoluble component, and the Yellowness Index (YI) measured on a 20 w/v% chloroform solution of the methanol-insoluble component with an absorption cell having an optical path length of 10cm is 0to 7.

In general, when the conversion at the end of polymerization is intended to be increased in batch-type radical polymerization, the amount of the oligomer component is increased in the final stage of polymerization, and the molding processability is considered to be adversely affected. In addition, it is considered that when a methacrylate monomer and an N-substituted maleimide monomer are copolymerized, the N-substituted maleimide monomer is generally likely to remain, and a low molecular weight polymer having a large N-substituted maleimide content is produced in the final stage of polymerization, and the polymer itself exhibits colorability or produces a polymer as a coloring component when heated.

In the polymerization of a methacrylic resin having a ring structure unit derived from an N-substituted maleimide monomer constituting the methacrylic resin molded product of the present embodiment, a polymerization initiator and/or a monomer is added during the polymerization, and the amount of the addition is controlled, whereby the variation in the concentration ratio of the monomer to the radical in the system during the polymerization can be reduced, the generation of low molecular weight components at the final stage of the polymerization can be suppressed, and the coloring property and the molding processability can be improved.

The first polymerization method is the following method: in the case of carrying out the polymerization in a batch or semi-batch manner, a radical polymerization initiator having a half-life of 1 minute or more and less than 60 minutes under a polymerization temperature condition is used as a radical polymerization initiator, and the radical polymerization initiator is added to a reactor while gradually decreasing the amount of the radical polymerization initiator added per unit time, thereby carrying out the polymerization of the monomers.

In a second polymerization mode, the following process is used: in the case of carrying out the polymerization in a batch or semi-batch manner, a radical polymerization initiator having a half-life under polymerization temperature conditions of 60 minutes or more is used as the radical polymerization initiator, and a part of the radical polymerization initiator is added to the reactor within a predetermined time after the start of the polymerization, and a part of the monomer is added to the reactor after a predetermined time after the start of the polymerization, thereby carrying out the polymerization.

Hereinafter, each polymerization method will be described.

In the first polymerization method, as described above, a radical polymerization initiator having a half-life of 1 minute or more and less than 60 minutes under a polymerization temperature condition is used as a radical polymerization initiator, and the monomer is polymerized by adding the radical polymerization initiator into a reactor while gradually decreasing the amount of the radical polymerization initiator added per unit time.

Here, a radical polymerization initiator having a half-life under polymerization temperature conditions of 1 minute or more and less than 60 minutes can also be referred to as a radical polymerization initiator having a polymerization temperature of 1 minute or less and more than 1 hour half-life temperature.

If the initiator has a half-life of 1 minute or more under the polymerization temperature condition, it is preferable to add the initiator to the polymerization reactor, mix the initiator with the content liquid sufficiently, and then decompose the initiator to start the polymerization. Further, by adding an initiator having a half-life significantly shorter than the polymerization time during the polymerization, it is possible to keep the variation of the ratio of the concentration of the residual monomer to the concentration of the radical in the reaction system small, and to keep the concentration of the radical low at the stage where the concentration of the residual monomer is decreased at the final stage of the polymerization, thereby suppressing the generation of low molecular weight components during the polymerization.

The half-life of the radical polymerization initiator under the polymerization temperature condition is preferably 3 minutes or more and less than 60 minutes, and more preferably 5 minutes or more and less than 60 minutes.

The 1 minute half-life temperature and the 1 hour half-life temperature are described in the literature, technical data of peroxide manufacturers, and the like, and the half-life temperature under other time conditions can be calculated by using the data of the activation energy of the decomposition reaction.

Examples of half-life temperatures for several free radical initiators are shown in table 1.

TABLE 1

In the first polymerization method, when the total amount of the radical polymerization initiators added during the polymerization period is 100% by mass, the amount of the initiators added after the time when the polymerization conversion rate reaches 85% is preferably 10to 25% by mass, and more preferably 10to 20% by mass.

Further, in the first polymerization method, a radical polymerization initiator having a half-life of 1 minute or more and less than 60 minutes under a polymerization temperature condition is used, and the radical polymerization initiator is added to the reactor while gradually decreasing the amount of the radical polymerization initiator added per unit time to carry out polymerization of the monomers, and in this case, the rate of addition of the initiator at the time when the polymerization conversion rate reaches 85% is preferably 1/10 to 1/3, more preferably 1/10 to 1/4, of the maximum rate of addition.

From the viewpoint of obtaining a sufficient conversion rate, the lower limit or more is preferable; from the viewpoint of suppressing the generation of a polymer component which adversely affects color tone and processability, the upper limit or less is preferable.

In the first polymerization method, a part of the monomer is charged into the reactor before the start of polymerization, and after the polymerization is started by adding the polymerization initiator, the remaining part of the monomer is supplied, whereby the production of both low molecular weight components and ultrahigh molecular weight components is suppressed, whereby the molecular weight distribution can be narrowed and the Mw/Mn and Mz/Mw can be adjusted to desired ranges. In addition, the amount of the N-substituted maleimide monomer remaining at the final stage of the polymerization can be reduced, and the color tone can be improved.

The ratio of the amount of the monomer initially charged to the amount of the monomer added after the start of polymerization is preferably 1: 9-8: 2, more preferably 2: 8-7.5: 2.5, more preferably 3: 7-5: 5.

in the first polymerization method, the amount of the methacrylate ester monomer which tends to be polymerized first in copolymerization is preferably small in the initial stage of addition and large in the additional stage of addition, so that the residual amount of the N-substituted maleimide monomer in the final stage of polymerization can be reduced, from the viewpoint of improvement of color tone.

In addition, the residual amount of the N-substituted maleimide monomer can be reduced by adding a monomer such as styrene having high alternating copolymerizability with the N-substituted maleimide monomer during the polymerization.

In the second polymerization method, as described above, a radical polymerization initiator having a half-life of 60 minutes or more under a polymerization temperature condition is used as the radical polymerization initiator, and a part of the radical polymerization initiator is added to the reactor within a predetermined time after the start of polymerization, and a part of the monomer is added after a predetermined time after the start of polymerization to perform polymerization.

When using free radical initiators having a half-life which is not significantly shorter than the polymerization time, the concentration of free radicals is kept relatively high even in the final stage of the polymerization.

In addition, by additionally adding a monomer at the final stage of the polymerization, the variation of the ratio of the residual monomer concentration to the radical concentration during the polymerization period can be reduced. Further, by adding a large amount of the radical initiator at the initial stage of polymerization, the radical concentration can be kept low at the stage where the residual monomer concentration at the final stage of polymerization is decreased, and thereby the generation of low molecular weight components during polymerization can be suppressed.

In the second polymerization method, 25 mass% or more, preferably 33 mass% or more, and more preferably 50 mass% or more of the total amount of the radical initiator is added within 30 minutes from the start of addition of the polymerization initiator.

Further, 30 minutes after the start of the addition of the polymerization initiator, 25 mass% or more of the total amount of the monomers added, preferably 33 mass% or more, more preferably 50 mass% or more, and still more preferably 66 mass% or more of the total amount of the monomers added are added.

Further, in the second polymerization method, the total addition amount of the radical initiator can be completed within 4 hours or less from the start of the addition of the polymerization initiator, more preferably within 3 hours or less from the start of the addition of the polymerization initiator, and further preferably within 2 hours or less from the start of the addition of the polymerization initiator.

In the first and second production methods of a methacrylic resin containing an N-substituted maleimide-based structural unit (B-1), the N-substituted maleimide-based structural unit (B-1) may be used as the structural unit (B) having a ring structure in its main chain, in combination with two or more kinds of radical initiators.

In the case where all of the half-lives under the polymerization temperature condition are 1 minute or more and less than 60 minutes, and in the case where all of the half-lives under the polymerization temperature condition are 60 minutes or more, the addition amounts and the addition rates of the radical initiators in the first polymerization method and the second polymerization method may be set to the total addition amount and the addition rate of the two or more radical initiators, respectively.

When a polymerization initiator having a half-life of 1 minute or more and less than 60 minutes under the polymerization temperature condition and a polymerization initiator having a half-life of 60 minutes or more under the polymerization temperature condition are used in combination, a second polymerization method is adopted in which 25% by mass or more of the total amount of addition of the radical polymerization initiator is added within 30 minutes from the start of addition of the polymerization initiator, and 25% by mass or more of the total amount of addition of the monomer is added 30 minutes after the start of addition of the polymerization initiator.

The method for recovering a polymer from a polymerization solution obtained by solution polymerization is not particularly limited, and the following methods can be mentioned: for example, a method of adding a polymerization liquid when a poor solvent such as a hydrocarbon-based solvent or an alcohol-based solvent that does not dissolve a polymerization product obtained by polymerization is present in excess, then treating (emulsifying and dispersing) the polymerization liquid with a homogenizer, and performing a pretreatment such as liquid-liquid extraction or solid-liquid extraction on an unreacted monomer to separate the monomer from the polymerization liquid; or a method of separating the polymerization solvent and unreacted monomers through a step called a devolatilization step to recover a polymerization product. Among them, the devolatilization step is preferably used from the viewpoint of productivity.

The devolatilization step is a step of removing volatile components such as a polymerization solvent, residual monomers, and reaction by-products under heating and reduced pressure.

Examples of the apparatus used in the devolatilization step include a devolatilization apparatus comprising a tubular heat exchanger and a devolatilization vessel; thin film evaporators such as waibouren (ワイブレン) and Ekuseba (エクセバ) manufactured by the company of stainless steel environment (the stainless steel environment ソリューション, Kobelco-Solutions co., Ltd), and Contra and tilt wing Contra manufactured by hitachi; a vented extruder having a residence time and surface area sufficient to exhibit devolatilization properties.

The devolatilization step and the like may be performed using a devolatilization apparatus in which two or more kinds of the above-described apparatuses are combined.

The treatment temperature in the devolatilization apparatus is preferably 150 to 350 ℃, more preferably 170 to 300 ℃, and still more preferably 200 to 280 ℃. By setting the temperature to the lower limit or higher, the residual volatile components can be suppressed, and by setting the temperature to the upper limit or lower, the coloration or decomposition of the obtained acrylic resin can be suppressed.

The degree of vacuum in the devolatilization apparatus can be in the range of 10to 500Torr, and is preferably in the range of 10to 300 Torr. By setting the degree of vacuum to an upper limit or less, the residual amount of volatile components can be suppressed. Further, it is realistic in terms of industrial implementation to set the degree of vacuum to a value not less than the lower limit.

The treatment time is appropriately selected depending on the amount of the residual volatile component, but the shorter the treatment time, the more preferable the treatment time is for suppressing coloring and decomposition of the obtained acrylic resin.

The polymer recovered through the devolatilization step is processed into pellets through a step called a pelletizing step.

In the granulating step, the molten resin is extruded into a strand form through a porous die, and the strand is processed into pellets by a cold cutting method, an air-heated cutting method, an underwater wire cutting method, and an underwater cutting method.

When an extruder with an exhaust port is used as the devolatilization apparatus, the devolatilization step and the granulation step can be performed simultaneously.

Hereinafter, a method for producing a methacrylic resin containing a lactone ring structure unit (B-2) as a structural unit (B) having a ring structure in its main chain will be described in detail.

As a method for producing a methacrylic resin having a lactone ring structure unit (B-2) in the main chain, which constitutes the methacrylic resin molded product of the present embodiment, solution polymerization using a solvent is preferable in terms of promoting a cyclization reaction. Here, a method of forming a lactone ring structure by a cyclization reaction after polymerization can be used.

Examples of the polymerization solvent to be used include aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; ketones such as methyl ethyl ketone and methyl isobutyl ketone.

The above solvents may be used singly or in combination of two or more.

The amount of the solvent used in the polymerization is not particularly limited as long as the polymerization is allowed to proceed and gelation can be suppressed, but is preferably 50 to 200 parts by mass, more preferably 100 to 200 parts by mass, based on 100 parts by mass of the total amount of the monomers to be blended, for example.

In order to sufficiently suppress gelation of the polymerization liquid and promote the cyclization reaction after polymerization, it is preferable to carry out polymerization so that the concentration of the produced polymer in the reaction mixture obtained after polymerization becomes 50 mass% or less.

Further, it is preferable to appropriately add a polymerization solvent to the reaction mixture and control the amount to 50% by mass or less. The method for adding the polymerization solvent to the reaction mixture is not particularly limited, and for example, the polymerization solvent may be added continuously or intermittently. The polymerization solvent to be added may be a single solvent or a mixed solvent of two or more kinds.

The polymerization temperature is not particularly limited as long as it is a temperature at which polymerization is carried out, but is preferably 50 to 200 ℃ and more preferably 80 to 180 ℃ from the viewpoint of productivity.

The polymerization time is not particularly limited as long as the target conversion rate is satisfied, but is preferably 0.5 to 10 hours, and more preferably 1 to 8 hours from the viewpoint of productivity and the like.

The polymerization conversion rate of the methacrylic resin having a lactone ring structure unit in the main chain, which constitutes the methacrylic resin molded product of the present embodiment, at the end of polymerization may be the polymerization conversion rate disclosed in the above-mentioned method for producing a methacrylic resin having a structural unit derived from an N-substituted maleimide monomer.

When the polymerization reaction is carried out, a chain transfer agent may be added as necessary to carry out the polymerization.

As the chain transfer agent, a chain transfer agent used in general radical polymerization can be used, and for example, a chain transfer agent disclosed in the above-described method for producing a methacrylic resin having a structural unit derived from an N-substituted maleimide monomer can be used.

The chain transfer agent may be used singly or in combination of two or more.

These chain transfer agents may be added at any stage as long as the polymerization reaction is in progress, and are not particularly limited.

The amount of the chain transfer agent to be added is not particularly limited as long as it is within a range that a desired degree of polymerization can be obtained under the polymerization conditions used, but is preferably 0.01 to 1 part by mass, more preferably 0.05 to 0.5 part by mass, based on 100 parts by mass of the total amount of the monomers used for polymerization.

The concentration of dissolved oxygen in the polymerization solution may be, for example, a value disclosed in the above-mentioned method for producing a methacrylic resin having a structural unit derived from an N-substituted maleimide monomer.

When the polymerization reaction is carried out, a polymerization initiator is added to carry out polymerization.

The polymerization initiator is not particularly limited, but, for example, the polymerization initiator disclosed in the above-described method for producing a methacrylic resin having a structural unit derived from an N-substituted maleimide monomer can be used.

The polymerization initiators may be used alone or in combination of two or more.

The amount of the polymerization initiator to be added may be appropriately set depending on the combination of monomers, reaction conditions, and the like, and is not particularly limited, but may be 0.01 to 1 part by mass, preferably 0.05 to 0.5 part by mass, based on 100 parts by mass of the total amount of the monomers to be used for polymerization.

In the polymerization of a methacrylic resin having a lactone ring structure unit constituting the methacrylic resin molded article of the present embodiment, a polymerization initiator and, if necessary, a monomer are added during the polymerization, and the amount of the monomer added is controlled, whereby the fluctuation of the ratio of the concentration of the monomer to the concentration of the radical in the system during the polymerization can be reduced, the generation of low molecular weight components at the final stage of the polymerization can be suppressed, and the coloring property and the molding processability can be improved.

The second polymerization method is the following method: in the case of carrying out the polymerization in a batch or semi-batch manner, a radical polymerization initiator having a half-life under polymerization temperature conditions of 60 minutes or more is used as the radical polymerization initiator, and a part of the radical polymerization initiator is added to the reactor within a predetermined time after the start of the polymerization, and a part of the monomer is added to the reactor after a predetermined time after the start of the polymerization, thereby carrying out the polymerization.

Hereinafter, each polymerization method will be described.

Examples of the meaning of the half-life temperature, the calculation method, and the half-life temperature of the radical initiator are as shown in the foregoing production method of the methacrylic resin having the structural unit derived from the N-substituted maleimide monomer.

In the first polymerization method, a part of the monomer is charged into the reactor before the start of the polymerization, and the remaining part of the monomer is supplied after the polymerization initiator is added to start the polymerization, whereby the formation of both low molecular weight components and ultrahigh molecular weight components is suppressed, whereby the molecular weight distribution can be narrowed and the Mw/Mn and Mz/Mw can be adjusted to desired ranges. Further, it is preferable to additionally add a monomer after the start of polymerization in view of the fact that the intramolecular cyclization ratio can be increased, gelation can be suppressed, and further color deterioration can be suppressed by introducing an acrylic monomer having a hydroxyl group into the molecule uniformly and as discontinuously as possible.

In addition, by additionally adding a monomer at the final stage of the polymerization, the variation of the ratio of the residual monomer concentration to the radical concentration during the polymerization period can be reduced. In addition, by adding a large amount of radical initiator at the initial stage of polymerization, the radical concentration can be kept low at the stage of the decrease in the residual monomer concentration at the final stage of polymerization, and thus the generation of low molecular weight components during polymerization can be suppressed.

In the second polymerization method, 50 mass% or more of the total amount of the radical initiator added is added within 30 minutes from the start of the addition of the polymerization initiator.

Further, 50 mass% or more, preferably 66 mass% or more of the total amount of the monomers added is added 30 minutes or less from the start of the addition of the polymerization initiator.

In the first and second production methods of the method for producing a methacrylic resin containing a lactone ring structural unit (B-2), two or more kinds of radical initiators can be used in combination, and the lactone ring structural unit (B-2) can be used as the structural unit (B) having a ring structure in its main chain.

When a polymerization initiator having a half-life of 1 minute or more and less than 60 minutes under the polymerization temperature condition and a polymerization initiator having a half-life of 60 minutes or more under the polymerization temperature condition are used in combination, a second polymerization method is adopted in which 50 mass% or more of the total amount of addition of the radical polymerization initiator is added within 30 minutes from the start of addition of the polymerization initiator, and 50 mass% or more of the total amount of addition of the monomer is added 30 minutes after the start of addition of the polymerization initiator.

The methacrylic resin having a lactone ring structure unit constituting the methacrylic resin molded product of the present embodiment can be obtained by performing a cyclization reaction after the completion of the polymerization reaction. Therefore, it is preferable to carry out the lactone cyclization reaction in a state containing a solvent without removing the polymerization solvent from the polymerization reaction liquid.

The copolymer obtained by polymerization is subjected to heat treatment to cause a cyclized condensation reaction between hydroxyl groups (hydroxyl groups) and ester groups present in the molecular chain of the copolymer, thereby forming a lactone ring structure.

In the case of performing the heat treatment for forming the lactone ring structure, a reaction apparatus equipped with a vacuum apparatus or a devolatilization apparatus for removing an alcohol which can be by-produced by the cyclized condensation, an extruder equipped with a devolatilization apparatus, or the like can be used.

When the lactone ring structure is formed, if necessary, a cyclized condensation catalyst may be used to perform a heat treatment in order to promote the cyclized condensation reaction.

Specific examples of the cyclized condensation catalyst include monoalkyl, dialkyl, and triesters of phosphorous acid such as methyl phosphite, ethyl phosphite, phenyl phosphite, dimethyl phosphite, diethyl phosphite, diphenyl phosphite, trimethyl phosphite, and triethyl phosphite; and monoalkyl, dialkyl, or trialkyl phosphates such as methyl phosphate, ethyl phosphate, 2-ethylhexyl phosphate, octyl phosphate, isodecyl phosphate, lauryl phosphate, stearyl phosphate, isostearyl phosphate, dimethyl phosphate, diethyl phosphate, di-2-ethylhexyl phosphate, diisodecyl phosphate, dilauryl phosphate, distearyl phosphate, diisostearyl phosphate, trimethyl phosphate, triethyl phosphate, triisodecyl phosphate, trilauryl phosphate, tristearyl phosphate, and triisostearyl phosphate.

The cyclized condensation catalyst may be used alone or in combination of two or more.

The amount of the cyclized condensation catalyst used is not particularly limited, and is, for example, preferably 0.01 to 3 parts by mass, and more preferably 0.05 to 1 part by mass, based on 100 parts by mass of the methacrylic resin.

When the amount is less than 0.01 part by mass, the reaction rate of the cyclized condensation reaction may not be sufficiently increased. On the other hand, when the amount of the catalyst used is more than 3 parts by mass, the resulting polymer may be colored or the polymer may be crosslinked, which may make melt molding difficult.

The addition timing of the cyclized condensation catalyst is not particularly limited, but may be, for example, added at the initial stage of the cyclized condensation reaction, added during the reaction, or added both at the initial stage and during the reaction.

When the cyclized condensation reaction is carried out in the presence of a solvent, it is preferable to carry out devolatilization simultaneously.

The apparatus used in the case of simultaneously carrying out the cyclized condensation reaction and the devolatilization step is not particularly limited, but a devolatilization apparatus comprising a heat exchanger and a devolatilization vessel, an extruder with an exhaust port, and an apparatus in which the devolatilization apparatus and the extruder are arranged in series are preferable, and a biaxial extruder with an exhaust port is more preferable.

As the vented twin-screw extruder used, a vented extruder having a plurality of vents is preferable.

The reaction treatment temperature when an extruder with an exhaust port is used is preferably 150 to 350 ℃, more preferably 200 to 300 ℃. When the reaction treatment temperature is less than 150 ℃ C, the cyclized condensation reaction is insufficient, and the residual volatile matter may increase. On the other hand, when the reaction treatment temperature is more than 350 ℃, the resulting polymer may be colored or decomposed.

The degree of vacuum in the case of using an extruder with an exhaust port is preferably 10to 500Torr, and more preferably 10to 300 Torr. When the degree of vacuum is more than 500Torr, volatile components tend to remain in some cases. On the other hand, when the degree of vacuum is less than 10Torr, the industrial implementation is sometimes difficult.

In carrying out the cyclized condensation reaction, it is preferable to add an alkaline earth metal and/or an amphoteric metal salt of an organic acid also at the time of granulation for the purpose of deactivating the remaining cyclized condensation catalyst.

Examples of the alkaline earth metal and/or amphoteric metal salt of the organic acid include calcium acetoacetate (calcium acetate), calcium stearate, zinc acetate, zinc octoate, and zinc 2-ethylhexyl acid.

After the cyclized condensation reaction step, the methacrylic resin is melt-extruded in a linear form from an extruder equipped with a multi-hole die, and is processed into pellets by a cold cutting method, an air-heated cutting method, an underwater linear cutting method, and an underwater cutting method

The lactonization for forming the lactone ring structure unit may be performed after the production of the resin and before the production of the resin composition (described later), or may be performed together with the melt-kneading of the resin and components other than the resin during the production of the resin composition.

The methacrylic resin constituting the methacrylic resin molded product of the present embodiment preferably has at least one ring structural unit selected from the group consisting of a structural unit derived from an N-substituted maleimide monomer and a lactone ring structural unit, and particularly preferably has a structural unit derived from an N-substituted maleimide monomer, from the viewpoint of facilitating high control of optical properties such as photoelastic coefficient without mixing with other thermoplastic resins.

(methacrylic resin composition)

The methacrylic resin composition constituting the methacrylic resin molded product of the present embodiment may contain the aforementioned methacrylic resin composition containing the methacrylic resin of the present embodiment. The methacrylic resin composition may optionally contain an additive in addition to the methacrylic resin of the present embodiment, and may further contain other thermoplastic resins, rubbery polymers, and the like in addition to the methacrylic resin.

Additives-

The methacrylic resin composition constituting the methacrylic resin molded product of the present embodiment may contain various additives within a range not significantly impairing the effects of the present invention.

Examples of the additives include, but are not particularly limited to, antioxidants, light stabilizers such as hindered amine light stabilizers, ultraviolet absorbers, mold release agents, other thermoplastic resins, paraffin process oils, naphthene process oils, aromatic process oils, softeners/plasticizers such as paraffin, organopolysiloxanes, mineral oils, inorganic fillers such as pigments such as flame retardants, antistatic agents, organic fibers, iron oxides, reinforcing agents such as glass fibers, carbon fibers, metal whiskers, and coloring agents; organic phosphorus compounds such as phosphites, phosphonites and phosphates, other additives, or mixtures thereof.

-antioxidant — -

The methacrylic resin composition constituting the methacrylic resin molded body of the present embodiment preferably contains an antioxidant which suppresses deterioration and coloring during molding or during use.

The antioxidant is not limited to the following, and examples thereof include hindered phenol antioxidants, phosphorus antioxidants, and sulfur antioxidants. The methacrylic resin of the present embodiment can be suitably used for various applications such as melt extrusion, injection molding, and film molding. The thermal history experienced during processing varies depending on the processing method, and there are various thermal histories from about several tens of seconds, such as from an extruder, to several tens of minutes to several hours, such as from molding of a thick member or sheet molding.

When a long thermal history is passed, the amount of the thermal stabilizer to be added needs to be increased in order to obtain desired thermal stability. From the viewpoint of suppressing the bleeding of the heat stabilizer and preventing the film from sticking to a roll in film formation, it is preferable to use a plurality of heat stabilizers in combination, and for example, it is preferable to use at least one selected from a phosphorus-based antioxidant and a sulfur-based antioxidant in combination with a hindered phenol-based antioxidant.

These antioxidants may be used singly or in combination of two or more.

Examples of the hindered phenol-based antioxidant include pentaerythritol tetrakis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ], thiodiethylene bis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ], octadecyl-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate, 3 ', 5, 5 ' -hexa-t-butyl-a, a ' - (mesityl-2, 4, 6-triyl) tri-p-cresol, 4, 6-bis (octylthiomethyl) o-cresol, 4, 6-bis (dodecylthiomethyl) o-cresol, ethylene bis (oxyethylene) bis [3- (5-t-butyl-4-hydroxy-m-tolyl) propionate ] (the above formula is not particularly limited to, Hexamethylenebis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], 1, 3, 5-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) -1, 3, 5-triazine-2, 4, 6(1H, 3H, 5H) -trione, 1, 3, 5-tris [ (4-tert-butyl-3-hydroxy-2, 6-xylene) methyl ] -1, 3, 5-triazine-2, 4, 6(1H, 3H, 5H) -trione, 2, 6-di-tert-butyl-4- (4, 6-bis (octylthio) -1, 3, 5-triazin-2-ylamine) phenol, 2- [1- (2-hydroxy-3, 5-di-t-pentylphenyl) ethyl ] -4, 6-di-t-pentylphenyl ester, 2-t-butyl-4-methyl-6- (2-hydroxy-3-t-butyl-5-methylbenzyl) phenyl acrylate, and the like.

Pentaerythritol tetrakis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], octadecyl-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate and 2- [1- (2-hydroxy-3, 5-di-tert-pentylphenyl) ethyl ] -4, 6-di-tert-pentylphenyl acrylate are particularly preferred.

Further, as the hindered phenol-based antioxidant of the above-mentioned antioxidants, commercially available phenol-based antioxidants can be used, and examples of such commercially available phenol-based antioxidants are not limited to Irganox (registered trademark) 1010(イルガノックス 1010: pentaerythrityl tetrakis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ], manufactured by BASF corporation, Irganox 1076(イルガノックス 1076: octadecyl-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate), manufactured by BASF corporation), Irganox 1330(イルガノックス 1330: 1330, 3 ', 5, 5 ' -hexat-butyl-a, a ' - (mesityl-2, 4, 6-triyl) tri-p-cresol, manufactured by BASF), Irganox 3114(イルガノックス 3114: 1, 3, 5-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) -1, 3, 5-triazine-2, 4, 6(1H, 3H, 5H) -trione, manufactured by BASF), Irganox 3125(イルガノックス 3125, manufactured by BASF), ADK STAB (registered trademark) AO-60(アデカスタブ AO-60, pentaerythrityl tetrakis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], manufactured by ADEKA), ADK STAB AO-80(3, 9-bis {2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy ] -1, 1-dimethylethyl } -2, 4, 8, 10-tetraoxaspiro [5, 5] undecane, manufactured by ADEKA corporation), Sumilizer (registered trademark) BHT (スミライザー BHT, manufactured by sumitomo chemical corporation), Cyanox (registered trademark) 1790(シアノックス 1790, manufactured by cyante corporation (サイテック)), Sumilizer GA-80(スミライザー GA-80, manufactured by sumitomo chemical corporation), Sumilizer GS (スミライザー: 2- [1- (2-hydroxy-3, 5-di-tert-pentylphenyl) ethyl ] -4, 6-di-tert-pentylphenyl acrylate, manufactured by Sumitomo chemical Co., Ltd.), submillizer GM (スミライザー GM: 2-tert-butyl-4-methyl-6- (2-hydroxy-3-tert-butyl-5-methylbenzyl) phenyl acrylate, manufactured by Sumitomo chemical Co., Ltd.), vitamin E (manufactured by Wako K.K. (エーザイ), and the like.

Among these commercially available phenol antioxidants, Irganox 1010, ADK STAB AO-60, ADK STAB AO-80, Irganox 1076, and Sumilizer GS are preferred from the viewpoint of the effect of the resin on thermal stability.

These antioxidants may be used alone or in combination of two or more.

Further, examples of the phosphorus-based antioxidant as the antioxidant include tris (2, 4-di-t-butylphenyl) phosphite, bis (2, 4-bis (1, 1-dimethylethyl) -6-methylphenyl) ethyl phosphite, tetrakis (2, 4-di-t-butylphenyl) (1, 1-biphenyl) -4, 4 '-diyl bisphosphonite, bis (2, 4-di-t-butylphenyl) pentaerythritol diphosphite, bis (2, 6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2, 4-dicumylphenyl) pentaerythritol diphosphite, tetrakis (2, 4-t-butylphenyl) (1, 1-biphenyl) -4, 4' -diyl bisphosphonite, and mixtures thereof, Di-tert-butyl-m-toluene-phosphonite, 4- [3- [ (2, 4, 8, 10-tetra-tert-butyldibenzo [ d, f ] [1, 3, 2] dioxaphosphepin) -6-yloxy ] propyl ] -2-methyl-6-tert-butylphenol, and the like.

Further, a commercially available phosphorus-based antioxidant may be used as the phosphorus-based antioxidant, and examples of the commercially available phosphorus-based antioxidant are not limited to Irgafos (registered trademark) 168(イルガフォス 168: tris (2, 4-di-t-butylphenyl) phosphite, manufactured by BASF corporation), Irgafos 12(イルガフォス 12: tris [2- [ [2, 4, 8, 10-tetra-t-butyldibenzo [ d, f ] [1, 3, 2] dioxaphosphepin-6-yl ] oxy ] ethyl ] amine, manufactured by BASF corporation), Irgafos 38(イルガフォス 38: bis (2, 4-bis (1, 1-dimethylethyl) -6-methylphenyl) ethyl phosphite, manufactured by BASF corporation), ADK STAB329K (アデカスタブ 329K, manufactured by ADEKA), ADK STABPEP-36(アデカスタブ PEP-36, manufactured by ADEKA), ADK STABPEP-36A (アデカスタブ PEP-36A, manufactured by ADEKA), ADK STABPEP-8(アデカスタブ PEP-8, manufactured by ADEKA), ADK STABHP-10(アデカスタブ HP-10, manufactured by ADEKA), ADK STAB2112(アデカスタブ 2112, manufactured by ADEKA), ADK STAB1178(アデカスタブ 1178, manufactured by ADEKA), ADK STAB1500(アデカスタブ 1500, manufactured by ADEKA), Sandstab P-EPQ (manufactured by Clarian (クラリアント), Weston618(ウェストン 618, manufactured by GE), Weston G (ウェストン 619G, manufactured by GE), Ultranox 626(ウルトラノックス 626, manufactured by GE), Sumilizer GP (スミライザー: 4- [3- [ (2, 4, 8, 10-tetra-tert-butyldibenzo [ d, f ] [1, 3, 2] dioxaphosphepin) -6-yloxy ] propyl ] -2-methyl-6-tert-butylphenol, manufactured by Sumitomo chemical Co., Ltd.), HCA (9, 10-dihydro-9-oxy-10-phosphaphenanthrene-10-oxide, manufactured by Sanko Co., Ltd.), and the like.

Among these commercially available phosphorus antioxidants, Irgafos 168, ADK STABPEP-36A, ADK STABHP-10 and ADK STAB1178 are preferable, and ADK STABPEP-36A and ADK STABPEP-36 are particularly preferable, from the viewpoint of the effect of imparting thermal stability to the resin and the effect of using a plurality of antioxidants in combination.

These phosphorus antioxidants may be used alone or in combination of two or more.

Examples of the sulfur-based antioxidant used as the antioxidant include, but are not limited to, 2, 4-bis (dodecylthiomethyl) -6-methylphenol (Irganox1726, manufactured by BASF), 2, 4-bis (octylthiomethyl) -6-methylphenol (Irganox1520L, manufactured by BASF), 2-bis { [3- (dodecylthio) -1-oxopropoxy ] methyl } propane-1, 3-diylbis [ 3-dodecylthio ] propionate ] (ADK BAO-412S, manufactured by ADEKA), 2-bis { [3- (dodecylthio) -1-oxopropoxy ] methyl } propane-1, 3-diylbis [ 3-dodecylthio ] propionate ] (KEMINOX), ケミノックス PLS, available from ケミプロ Kasei corporation, ditridecyl 3, 3' -thiodipropionate (AO-503, manufactured by ADEKA corporation), and the like.

Among these commercially available sulfur antioxidants, ADK STABAO-412S and KEMINOX PLS are preferable from the viewpoints of the effect of imparting thermal stability to the resin, the effect of using a plurality of antioxidants in combination, and the workability.

These sulfur-based antioxidants may be used alone or in combination of two or more.

The content of the antioxidant is not more than 5 parts by mass, more preferably not more than 3 parts by mass, still more preferably not more than 1 part by mass, still more preferably not more than 0.8 part by mass, still more preferably 0.01 to 0.8 part by mass, and particularly preferably 0.01 to 0.5 part by mass, based on 100 parts by mass of the methacrylic resin, because the content may cause problems such as bleeding during processing.

The timing of adding the antioxidant is not particularly limited, and examples thereof include a method of starting polymerization after adding to a monomer solution before polymerization, a method of adding to a polymer solution after polymerization and mixing and then subjecting to a devolatilization step, a method of adding to a polymer in a molten state after devolatilization and mixing and then granulating, a method of adding to and mixing when devolatilizing and granulating the granules after melt extrusion again, and the like. In the above method, from the viewpoint of preventing thermal deterioration and coloration in the devolatilization step, it is preferable that the polymer solution after polymerization is added to and mixed with an antioxidant before the devolatilization step, and then the mixture is subjected to the devolatilization step.

- - (hindered amine-based light stabilizer- -

The methacrylic resin composition constituting the methacrylic resin molded product of the present embodiment may contain a hindered amine light stabilizer.

The hindered amine-based light stabilizer is not particularly limited, and is preferably a compound having 3 or more ring structures. Here, the ring structure is preferably at least one selected from the group consisting of an aromatic ring, an aliphatic ring, an aromatic heterocyclic ring and a non-aromatic heterocyclic ring, and when two or more ring structures are included in one compound, the ring structures may be the same or different from each other.

The hindered amine-based light stabilizer is not limited to the following, and specific examples thereof include bis (1,2,2,6, 6-pentamethyl-4-piperidyl) bis [ [3, 5-bis (1, 1-dimethylethyl) -4-hydroxyphenyl ] methyl ] butylmalonate, a mixture of bis (1,2,2,6, 6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6, 6-pentamethyl-4-piperidyl sebacate, bis (2, 2,6, 6-tetramethyl-4-piperidyl) sebacate, N '-bis (2, 2,6, 6-tetramethyl-4-piperidyl) -N, N' -diformylhexamethylenediamine, dibutylamine/1, a polycondensate of 3, 5-triazine/N, N '-bis (2, 2,6, 6-tetramethyl-4-piperidyl-1, 6-hexamethylenediamine with N- (2, 2,6, 6-tetramethyl-4-piperidyl) butylamine, poly [ {6- (1,1, 3, 3-tetramethylbutyl) amino-1, 3, 5-triazine-2, 4-diyl } {2, 2,6, 6-tetramethyl-4-piperidyl) imino } hexamethylene { (2, 2,6, 6-tetramethyl-4-piperidyl) imino } ], tetrakis (1,2,2,6, 6-pentamethyl-4-piperidyl) butane-1, 2, 3, 4-tetracarboxylic acid ester, N, N' -bis (2, 2,6, 6-tetramethyl-4-piperidyl) butylamine, Tetrakis (2, 2,6, 6-tetramethyl-4-piperidyl) butane-1, 2, 3, 4-tetracarboxylic acid ester, a reactant of 1,2,2,6, 6-pentamethyl-4-piperidinol with β, β, β ', β' -tetramethyl-2, 4, 8, 10-tetraoxaspiro [5.5] undecane-3, 9-diethanol, a reactant of 2,2,6, 6-tetramethyl-4-piperidinol with β, β, β ', β' -tetramethyl-2, 4, 8, 10-tetraoxaspiro [5.5] undecane-3, 9-diethanol, bis (1-undecyloxy-2, 2,6, 6-tetramethylpiperidin-4-yl) carbonate, 1,2,2,6, 6-pentamethyl-4-piperidinemethyl acrylate, a, 2,2,6, 6-tetramethyl-4-piperidylmethacrylate and the like.

Among them, preferred are bis (1,2,2,6, 6-pentamethyl-4-piperidyl) esters of [ [3, 5-bis (1, 1-dimethylethyl) -4-hydroxyphenyl ] methyl ] butylmalonic acid having three or more ring structures, dibutylamine/1, 3, 5-triazine/N, N' -bis (2, 2,6, 6-tetramethyl-4-piperidyl-1, 6-hexamethylenediamine and N- (2, 2,6, 6-tetramethyl-4-piperidyl) butylamine, poly [ {6- (1,1, 3, 3-tetramethylbutyl) amino-1, 3, 5-triazine-2, 4-diyl } {2, 2,6, 6-tetramethyl-4-piperidyl) imino } hexamethylene { (2, 2,6, 6-tetramethyl-4-piperidyl) imino } ], a reactant of 1,2,2,6, 6-pentamethyl-4-piperidinol and β, β, β ', β' -tetramethyl-2, 4, 8, 10-tetraoxaspiro [5.5] undecane-3, 9-diethanol, a reactant of 2,2,6, 6-tetramethyl-4-piperidinol and β, β, β ', β' -tetramethyl-2, 4, 8, 10-tetraoxaspiro [5.5] undecane-3, 9-diethanol.

The content of the hindered amine-based light stabilizer is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, further preferably 1 part by mass or less, further more preferably 0.8 part by mass or less, further preferably 0.01 to 0.8 part by mass, and particularly preferably 0.01 to 0.5 part by mass, based on 100 parts by mass of the methacrylic resin, because an excessive content may cause problems such as bleeding during processing.

-UV absorber — (UV absorber) —

The methacrylic resin composition constituting the methacrylic resin molded product of the present embodiment may contain an ultraviolet absorber.

The ultraviolet absorber is not particularly limited, but is preferably an ultraviolet absorber having a maximum absorption wavelength of 280 to 380nm, and examples thereof include benzotriazole compounds, benzotriazine compounds, benzophenone compounds, oxybenzophenone compounds, benzoate compounds, phenol compounds, oxazole compounds, cyanoacrylate compounds, and benzoxazinone compounds.

Examples of the benzotriazole-based compound include 2, 2' -methylenebis [4- (1,1, 3, 3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol ], 2- (3, 5-di-tert-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -p-cresol, 2- (2H-benzotriazol-2-yl) -4, 6-bis (1-methyl-1-phenylethyl) phenol, 2-benzotriazol-2-yl-4, 6-di-tert-butylphenol, 2- [ 5-chloro (2H) -benzotriazol-2-yl ] -4-methyl-6-tert-butylphenol, and mixtures thereof, 2- (2H-benzotriazol-2-yl) -4, 6-di-tert-butylphenol, 2- (2H-benzotriazol-2-yl) -4- (1,1, 3, 3-tetramethylbutyl) phenol, 2- (2H-benzotriazol-2-yl) -4-methyl-6- (3, 4, 5, 6-tetrahydrophthalimidomethyl) phenol, a reaction product of methyl 3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate/polyethylene glycol 300, 2- (2H-benzotriazol-2-yl) -6- (linear and side-chain dodecyl) -4-methylphenol, a mixture of two or more of these, and a mixture of two or more of these, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [ 2-hydroxy-3, 5-bis (. alpha.,. alpha. -dimethylbenzyl) phenyl ] -2H-benzotriazole, 3- (2H-benzotriazol-2-yl) -5- (1, 1-dimethylethyl) -4-hydroxy-C7-9 side chain, and straight chain alkyl esters.

Among the above, benzotriazole-based compounds having a molecular weight of 400 or more are preferable, and examples of commercially available products include Kemisorb (registered trademark) 2792 (manufactured by Chemipro Kasei Kaisha, Ltd, ケミプロ), ADK STAB (registered trademark) LA31 (manufactured by ADEKA), TINUVIN (registered trademark) 234 (manufactured by BASF).

Examples of the benzotriazine-based compound include a 2-mono (hydroxyphenyl) -1, 3, 5-triazine compound, a 2, 4-bis (hydroxyphenyl) -1, 3, 5-triazine compound, and a 2, 4, 6-tris (hydroxyphenyl) -1, 3, 5-triazine compound, and specifically, there are exemplified a 2, 4-diphenyl-6- (2-hydroxy-4-methoxyphenyl) -1, 3, 5-triazine, a 2, 4-diphenyl-6- (2-hydroxy-4-ethoxyphenyl) -1, 3, 5-triazine, a 2, 4-diphenyl- (2-hydroxy-4-propoxyphenyl) -1, 3, 5-triazine, a, 2, 4-diphenyl- (2-hydroxy-4-butoxyphenyl) -1, 3, 5-triazine, 2, 4-diphenyl-6- (2-hydroxy-4-hexyloxyphenyl) -1, 3, 5-triazine, 2, 4-diphenyl-6- (2-hydroxy-4-octyloxyphenyl) -1, 3, 5-triazine, 2, 4-diphenyl-6- (2-hydroxy-4-dodecyloxyphenyl) -1, 3, 5-triazine, 2, 4-diphenyl-6- (2-hydroxy-4-benzyloxyphenyl) -1, 3, 5-triazine, 2, 4-diphenyl-6- (2-hydroxy-4-butoxyethoxy) -1, 3, 5-triazine, 2, 4-bis (2-hydroxy-4-butoxyphenyl) -6- (2, 4-dibutoxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-4-methoxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-4-ethoxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-4-propoxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-4-butoxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-4-hexyloxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-4-octyloxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-4-dodecyloxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-4-benzyloxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-4-ethoxyethoxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-4-butoxyethoxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-4-propoxyethoxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-4-methoxycarbonylpropyloxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-4-ethoxycarbonylethyloxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-4- (1- (2-ethoxyhexyloxy) -1-oxopropane -2-yloxy) phenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-3-methyl-4-methoxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-3-methyl-4-ethoxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-3-methyl-4-propoxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-3-methyl-4-butoxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-3-methyl-4-hexyloxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-3-methyl-4-octyloxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-3-methyl-4-dodecyloxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-3-methyl-4-benzyloxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-3-methyl-4-ethoxyethoxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-3-methyl-4-butoxyethoxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-3-methyl-4-propoxyethoxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-3-methyl-4-methoxycarbonylpropyloxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-3-methyl-4-ethoxycarbonylethyloxyphenyl) -1, 3, 5-triazine, 2, 4, 6-tris (2-hydroxy-3-methyl-4- (1- (2-ethoxyhexyloxy) -1, 3, 5-triazine -oxopropan-2-yloxy) phenyl) -1, 3, 5-triazine and the like.

As the benzotriazine-based compound, commercially available products can be used, and examples thereof include Kemisorb 102 (manufactured by Chemipro Kasei Kaisha, Ltd.), LA-F70 (manufactured by ADEKA), LA-46 (manufactured by ADEKA), TINUVIN 405 (manufactured by BASF), TINUVIN 460 (manufactured by BASF), TINUVIN 47VIN 9 (manufactured by BASF), and TINUVIN 1577FF (manufactured by BASF).

Among them, from the viewpoint of high compatibility with acrylic resins and excellent ultraviolet absorption characteristics, an ultraviolet absorber having a 2, 4-bis (2, 4-dimethylphenyl) -6- [ 2-hydroxy-4- (3-alkoxy-2-hydroxypropyloxy) -5- α -cumylphenyl ] -s-triazine skeleton ("alkoxy" means a long-chain alkoxy group such as an octyloxy group, a nonyloxy group, or a decyloxy group) can be more preferably used.

As the ultraviolet absorber, in particular, from the viewpoint of compatibility with a resin and volatility upon heating, a benzotriazole-based compound or a benzotriazine-based compound having a molecular weight of 400 or more is preferable, and from the viewpoint of suppressing decomposition of the ultraviolet absorber itself by heating at the time of extrusion processing, a benzotriazine-based compound is particularly preferable.

The melting point (Tm) of the ultraviolet absorber is preferably 80 ℃ or higher, more preferably 100 ℃ or higher, still more preferably 130 ℃ or higher, and still more preferably 160 ℃ or higher.

The weight loss ratio of the ultraviolet absorber when the temperature is raised from 23 ℃ to 260 ℃ at a rate of 20 ℃/min is preferably 50% or less, more preferably 30% or less, still more preferably 15% or less, still more preferably 10% or less, and still more preferably 5% or less.

These ultraviolet absorbers may be used alone or in combination of two or more. By combining two ultraviolet absorbers having different structures, ultraviolet rays in a wide wavelength region can be absorbed.

The content of the ultraviolet absorber is not particularly limited as long as it does not interfere with heat resistance, moist heat resistance, thermal stability and moldability and exhibits the effects of the present invention, and is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 4 parts by mass, further preferably 0.25 to 3 parts by mass, and further more preferably 0.3 to 3 parts by mass, relative to 100 parts by mass of the methacrylic resin. When the content of the ultraviolet absorber is within the above range, the balance of ultraviolet absorption performance, moldability, and the like is excellent.

-mold release agent —

The methacrylic resin composition constituting the methacrylic resin molded body of the present embodiment may contain a release agent. The release agent is not limited to the following, and examples thereof include fatty acid esters, fatty acid amides, fatty acid metal salts, hydrocarbon lubricants, alcohol lubricants, polyalkylene glycols or carboxylic acid esters, hydrocarbon paraffin mineral oils, and the like.

The fatty acid ester usable as the release agent is not particularly limited, and conventionally known ones can be used.

Examples of the fatty acid ester include ester compounds of fatty acids having 12 to 32 carbon atoms such as lauric acid, palmitic acid, heptadecanoic acid, stearic acid, oleic acid, arachidic acid, and behenic acid, and monohydric aliphatic alcohols such as palmitic alcohol, stearyl alcohol, and behenyl alcohol, and polyhydric aliphatic alcohols such as glycerol, pentaerythritol, dipentaerythritol, and sorbitan, and complex ester compounds of fatty acids and polybasic organic acids, and monohydric aliphatic alcohols or polyhydric aliphatic alcohols.

As such a fatty acid ester-based lubricant, for example, there can be exemplified cetyl palmitate, butyl stearate, stearyl citrate, glyceryl monocaprylate, glyceryl monocaprate, glyceryl monolaurate, glyceryl monopalmitate, glyceryl dipalmitate, glyceryl monostearate, glyceryl distearate, glyceryl tristearate, glyceryl monooleate, glyceryl dioleate, glyceryl trioleate, glyceryl monolinoleate, glyceryl monobehenate, glyceryl mono 12-hydroxystearate, glyceryl di 12-hydroxystearate, glyceryl tri 12-hydroxystearate, glyceryl diacetyl monostearate, glyceryl citric acid fatty ester, pentaerythritol adipic acid stearate, montanic acid partial saponification ester, pentaerythritol tetrastearate, dipentaerythritol hexastearate, sorbitan tristearate and the like.

These fatty acid ester-based lubricants may be used singly or in combination of two or more.

Examples of commercially available products include RIKEMAL (リケマール, registered trademark) series, Poem (ポエム, registered trademark) series, RIKESTER (リケスター, registered trademark) series, RIKEMASTER (リケマスター, registered trademark) series, EXCEL (エキセル, registered trademark) series, rheeodol (レオドール, registered trademark) series, excoparl (エキセパール, registered trademark) series, and cocoard (ココナード, registered trademark) series, which are manufactured by rikawa vitamin corporation (rikawa ビタミン, co), examples thereof include RIKEMAL S-100, RIKEMAL H-100, Poem V-100, RIKEMAL B-100, RIKEMAL HC-100, RIKEMAL S-200, Poem B-200, RIKESTER EW-200, RIKESTER EW-400, EXCELS-95, RHEODOL MS-50 and the like.

The fatty acid amide-based lubricant is not particularly limited, and conventionally known fatty acid amide-based lubricants can be used.

Examples of the fatty acid amide-based lubricant include saturated fatty acid amides such as lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide; unsaturated fatty acid amides such as oleamide, erucamide, and ricinoleamide; substituted amides such as N-stearyl stearic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucamide, and N-oleyl palmitic acid amide; methylol amides such as methylol stearic acid amide and methylol behenic acid amide; saturated fatty acid bisamides such as methylene bisstearamide, ethylene bisdecanoic acid amide, ethylene bislauric acid amide, ethylene bisstearamide (ethylene bisstearylamide), ethylene bisisostearamide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearamide, hexamethylene bisbehenic acid amide, hexamethylene bishydroxystearic acid amide, N '-distearyladipic acid amide, and N, N' -distearylsebacic acid amide; unsaturated fatty acid bisamides such as ethylenebisoleic acid amide, hexamethylenebisoleic acid amide, N '-dioleyl adipic acid amide, and N, N' -dioleyl sebacic acid amide; and aromatic bisamides such as m-xylylene bisstearic acid amide and N, N' -distearyl isophthalic acid amide.

These fatty acid amide-based release agents may be used singly or in combination of two or more.

Examples of commercially available products include DIAMIDO (ダイヤミッド, registered trademark) series (manufactured by japan chemical industry corporation), amide series (manufactured by japan chemical industry corporation), Nikka amid (ニッカアマイド, registered trademark) series (manufactured by japan chemical industry corporation), methylolamide series, bisamide series, slip (スリパックス, registered trademark) series (manufactured by japan chemical industry corporation), royal wax (カオーワックス) series (manufactured by royal corporation), fatty acid amide series (manufactured by royal corporation), and ethylenebisstearamide series (manufactured by japanese chemical industry corporation).

The fatty acid metal salt is a metal salt of a higher fatty acid, and examples thereof include lithium stearate, magnesium stearate, calcium laurate, calcium ricinoleate, strontium stearate, barium laurate, barium ricinoleate, zinc stearate, zinc laurate, zinc ricinoleate, zinc 2-ethyl hexoate, lead stearate, 2-basic lead stearate, lead naphthenate, calcium 12-hydroxystearate, and lithium 12-hydroxystearate.

Examples of commercially available products include SZ series, SC series, SM series, and SA series manufactured by sakai chemical industry corporation.

From the viewpoint of maintaining transparency, the content of the fatty acid metal salt is preferably 0.2% by mass or less with respect to 100% by mass of the methacrylic resin composition.

The release agent may be used alone or in combination of two or more.

As the release agent to be used, a release agent having a decomposition start temperature of 200 ℃ or higher is preferable. The decomposition initiation temperature can be measured by using the 1% weight loss temperature of TGA.

The content of the release agent is not limited as long as the effect as a release agent can be obtained, and when the content is excessive, there is a risk that problems such as bleeding out and poor extrusion due to screw sliding occur during processing, and therefore, it is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, further preferably 1 part by mass or less, further more preferably 0.8 parts by mass or less, further preferably 0.01 to 0.8 parts by mass, and particularly preferably 0.01 to 0.5 parts by mass, relative to 100 parts by mass of the methacrylic resin. When the amount is in the above range, it is preferable to suppress the decrease in transparency due to the addition of the release agent, and to suppress the release failure at the time of injection molding and the tendency of the sheet to stick to the metal roll at the time of molding.

Other thermoplastic resins

The methacrylic resin composition constituting the methacrylic resin molded body of the present embodiment may contain a thermoplastic resin other than the methacrylic resin for the purpose of adjusting the birefringence and improving the flexibility without impairing the object of the present invention.

Examples of the other thermoplastic resin include polyacrylates such as polybutylacrylate; styrene polymers such as polystyrene, styrene-methyl methacrylate copolymers, styrene-butyl acrylate copolymers, styrene-acrylonitrile copolymers, and acrylonitrile-butadiene-styrene block copolymers; further, there may be mentioned, for example, acrylic rubber particles having a3 to 4-layer structure as described in, for example, JP-A59-202213, JP-A63-27516, JP-A51-129449, JP-A52-56150 and the like; rubbery polymers disclosed in JP-B-60-17406 and JP-A-8-245854; and (3) methacrylic rubber-containing graft copolymer particles obtained by multistage polymerization as described in International publication No. 2014-002491.

Among them, from the viewpoint of obtaining good optical properties and mechanical properties, styrene-acrylonitrile copolymers and rubber-containing graft copolymer particles having a surface layer with a graft portion composed of a composition compatible with a methacrylic resin containing a structural unit (X) having a ring structure in the main chain are preferable.

The average particle diameter of the acrylic rubber particles, the graft copolymer particles containing a methacrylic rubber, and the rubbery polymer is preferably 0.03 to 1 μm, and more preferably 0.05 to 0.5 μm, from the viewpoint of improving the impact strength, optical properties, and the like of the film obtained from the composition of the present embodiment.

The content of the other thermoplastic resin is preferably 0to 50 parts by mass, more preferably 0to 25 parts by mass, based on 100 parts by mass of the methacrylic resin.

(method for producing methacrylic resin composition)

Examples of the method for producing the methacrylic resin composition include a method of kneading the composition using a kneading machine such as an extruder, a heating roll, a kneader, a roll mixer (roll mixer) or a banbury mixer. Among them, from the viewpoint of productivity, it is preferable to perform kneading by an extruder. The kneading temperature may be set according to a preferable processing temperature of the polymer constituting the methacrylic resin and the other resin to be mixed, and is, as a standard, in the range of 140 to 300 ℃, preferably 180 to 280 ℃. In addition, the extruder is preferably provided with a vent for the purpose of reducing volatile components.

Glass transition temperature (Tg) of methacrylic resin compositionThe ratio of the amount of the methanol-soluble component to the total amount of the methanol-soluble component and the methanol-insoluble component of 100% by mass, the Yellowness Index (YI) of the methanol-insoluble component, the 680nm transmittance, the Z-average molecular weight (Mz), the weight-average molecular weight (Mw), the number-average molecular weight (Mn), and the photoelastic coefficient C_RThe same can be set as described above for the methacrylic resin.

(method for producing methacrylic resin molded article)

As a method for producing a methacrylic resin molded product, various molding methods such as extrusion molding, injection molding, compression molding, calender molding, inflation molding, and blow molding can be used.

Various molded articles using the methacrylic resin and the resin composition thereof according to the present embodiment can be further subjected to surface functionalization treatment such as antireflection treatment, transparent conductive treatment, electromagnetic wave shielding treatment, and gas barrier treatment.

(characteristics of methacrylic resin molded article)

The characteristics of the methacrylic resin molded product of the present embodiment will be described below.

In the methacrylic resin molded article of the present embodiment, YI under the condition that the optical path length is 3mm is preferably 0to 2.5, more preferably 0.5 to 2.2, and further preferably 0.7 to 2.0.

The total light transmittance under the condition of an optical path length of 3mm measured under the same conditions as those for the above YI is preferably 90to 94%, more preferably 91 to 93%, and still more preferably 91.5 to 93%.

By setting YI and total light transmittance in the condition of an optical path length of 3mm within the above ranges, a practically sufficient color tone and transmittance can be obtained in a relatively thin molded article such as a sheet.

YI and the total light transmittance under the condition that the optical path length is 3mm can be measured by the methods described in the examples below.

In the methacrylic resin molded article of the present embodiment, YI under the condition that the optical path length is 80mm is preferably 0to 35, more preferably 1 to 30, and further preferably 2 to 30.

Further, as an index of the visual transmittance, the Y value under the condition that the optical path length measured under the same condition as the YI measurement condition is 80mm is preferably 60 to 95, more preferably 65 to 93, and further preferably 68 to 90.

By setting the YI and Y values in the above range under the condition that the optical path length is 80mm, the color tone and transparency suitable for the use of the molded article having an optical path such as a light guide plate can be obtained.

The YI and Y values under the condition that the optical path length is 80mm can be measured by the method described in the examples below.

(use of methacrylic resin molded article)

Examples of uses of the methacrylic resin molded article include sanitary uses such as household goods, OA equipment, AV equipment, battery electric equipment, lighting equipment, automobile parts, housings, and sanitary substitutes for sanitary ware, and uses such as optical parts.

Examples of the automobile member include a tail lamp, an instrument cover, a headlamp, a light guide bar, a lens, a front panel for car navigation, and the like.

Examples of the optical member include a light guide plate, a diffusion plate, a polarizing plate protective film, a retardation film such as a 1/4 wavelength plate, a 1/2 wavelength plate, a viewing angle control film, a liquid crystal optical compensation film, and the like used for displays such as a liquid crystal display, a plasma display, an organic EL display, a field emission display, a rear projection television, and the like, a display front panel, a display substrate, a lens, a touch panel, and the like, and can be suitably used for a transparent substrate used for a solar cell, and the like. Further, the present invention can be used for a waveguide, a lens, an optical fiber, a coating material for an optical fiber, a lens of an LED, a lens cover, and the like in the field of an optical communication system, an optical exchange system, and an optical measurement system, or in an optical product such as a head mounted display and a liquid crystal projector. Moreover, it can be used as a modifying material for other resins.

Examples

The present invention will be described in detail below with reference to examples and comparative examples. It should be noted that the present invention is not limited to the following examples.

< 1. measurement of polymerization conversion >

A part of the polymerization solution in production examples and production comparative examples was collected, a 5 mass% solution was prepared by dissolving a sample in chloroform with respect to the amount of monomers remaining in the polymerization solution sample, n-decane was added as an internal standard, and the concentration of monomers remaining in the sample was measured by gas chromatography (GC-2010, shimadzu corporation) to obtain the total mass (a) of monomers remaining in the polymerization solution. Then, the polymerization conversion (%) was determined from the total mass (a), the total mass (b) assuming that the monomers added up to the time of sampling remained in the total amount in the polymerization solution, and the total mass (c) of the monomers added up to the end of the polymerization step, by calculating the formula (b-a)/c × 100.

< 2. analysis of structural units >

In each of the production examples described later, unless otherwise specified¹H-NMR measurement and¹³the structural units of the methacrylic resin produced in the production examples described later were identified by C-NMR measurement, and the amount of the structural units present was calculated.¹H-NMR measurement and¹³the measurement conditions for the C-NMR measurement are as follows.

The measurement device: DPX-400 manufactured by Bruker (ブルーカー Co., Ltd.)

Determination of the solvent: CDCl₃Or DMSO-d₆

Measurement temperature: 40 deg.C

When the ring structure of the methacrylic resin is a lactone ring structure, it has been confirmed by the methods described in jp 2001-151814 a and jp 2007-297620 a.

<3. measurement of molecular weight and molecular weight distribution >

The Z-average molecular weight (Mz), the weight-average molecular weight (Mw), and the number-average molecular weight (Mn) of the methacrylic resin produced in the production examples described below were measured by the following apparatus and conditions.

The measurement device: gel permeation chromatograph (HLC-8320GPC) manufactured by Tosoh corporation (DONG ソー Co., Ltd.)

Measurement conditions:

column: TSKguardcolumn SuperH-H1 root, TSKgel SuperHM-M2 root and TSKgel SuperH 25001 root are used in series in sequence. Column temperature: at 40 ℃.

Developing solvent: tetrahydrofuran, flow rate; 0.6 mL/min, as an internal standard, 0.1g/L of 2, 6-di-tert-butyl-4-methylphenol (BHT) was added.

A detector: RI (differential refraction) detector, detection sensitivity: 3.0 mV/min.

Sample preparation: 0.02g of a methacrylic resin or a 20mL tetrahydrofuran solution of a methacrylic resin. Injection amount: 10 μ L.

Calibration curve standard samples: the following 10 types of polymethyl methacrylate (manufactured by Polymer Laboratories, PMMA Calibration Kit M-M-10 (product model number)) which are monodisperse, have known weight peak molecular weights and different molecular weights were used.

Weight Peak molecular weight (Mp)

Under the above conditions, the RI detection intensity with respect to the elution time of the methacrylic resin was measured.

Based on the calibration curve obtained by measuring the calibration curve standard sample, the Z-average molecular weight (Mz), the weight-average molecular weight (Mw), and the number-average molecular weight (Mn) of the methacrylic resin and the methacrylic resin were determined.

< 4. glass transition temperature >

The glass transition temperature (Tg) (. degree. C.) of a methacrylic resin was measured in accordance with JIS-K7121.

First, the sample was conditioned in a standard state (23 ℃ C., 65% RH) (left at 23 ℃ C. for 1 week), and about 10mg of the conditioned sample was cut out from 4 sites (4 positions) to prepare test pieces.

Then, under the condition of a nitrogen flow rate of 25 mL/min, measurement was performed using a differential scanning calorimeter (Diamond DSC, manufactured by Perkin Elmer, Japan) in which the temperature was raised from room temperature (23 ℃) to 200 ℃ at 10 ℃/min (first temperature rise), the sample was kept at 200 ℃ for 5 minutes, the sample was completely dissolved, then the temperature was lowered from 200 ℃ to 40 ℃ at 10 ℃/min, the sample was kept at 40 ℃ for 5 minutes, and further, temperature was raised again (second temperature rise) under the temperature rise condition described above, and in the DSC curve drawn at this time, the intersection point (midpoint glass transition temperature) between the curve of the stepwise change portion at the second temperature rise and the straight line equidistant from the extension lines of the respective base lines in the vertical axis direction was measured as the glass transition temperature (Tg) (. degree. C.). The measurement was performed at 4 points for each sample, and the arithmetic average (rounded up or down in decimal places) of the 4 points was taken as the measurement value.

Less than 5, photoelastic coefficient C_RMeasurement of

The methacrylic resins obtained in production examples and production comparative examples were molded into a film by a vacuum compression molding machine to produce a sample for measurement.

As concrete conditions for preparing the sample, a vacuum compression molding machine (SFV-30, product of the Shenteng Metal industry) was used, the preheating was carried out at 260 ℃ under reduced pressure (about 10kPa) for 10 minutes, then the resin was compressed at 260 ℃ under about 10MPa for 5 minutes, and after the decompression and release of the pressure, the resin was transferred to a compression molding machine for cooling and solidification. The pressed film thus obtained was cured in a constant temperature and humidity chamber adjusted to 23 ℃ and a humidity of 60% for 24 hours or more, and then a test piece for measurement (thickness: about 150 μm, width: 6mm) was cut out.

The photoelastic coefficient C was measured using a birefringence measurement apparatus having a detailed description in Polymer Engineering and Science 1999,39,2349-2357_R(Pa^-1)。

The film-like test piece was placed in a film stretching apparatus (manufactured by Hakka cell) also installed in the constant temperature and humidity chamber so that the distance between the clamps became 50 mm. Then, a birefringence measurement device (RETS-100, manufactured by Otsuka Denshi Co., Ltd.) was disposed so that the laser beam path was positioned at the center of the film, and a tensile stress was applied at a strain rate of 50%/min (clamp pitch: 50 mm; clamp moving speed: 5 mm/min) to measure the birefringence of the test piece.

Based on the absolute value (| Deltan |) of birefringence and the tensile stress (σ) obtained by the measurement_R) The slope of the straight line is obtained by least square approximation, and the photoelastic coefficient (C) is calculated_R)(Pa^-1). When calculating, the tensile stress is 2.5 MPa-sigma_RData less than or equal to 10 MPa.

C_R＝|Δn|/σ_R

Here, the absolute value (| Δ n |) of birefringence represents the value shown below.

|Δn|＝|nx-ny|

(nx: refractive index in stretching direction; ny: refractive index in a direction perpendicular to the stretching direction in plane)

< 6. measurement of amount of methanol-soluble component and amount of methanol-insoluble component >

After 5g of the methacrylic resin obtained in production examples and production comparative examples was dissolved in 100mL of chloroform, the solution was put into a dropping funnel, and 1L of methanol stirred with a stirrer was added dropwise over about 1 hour to reprecipitate. After the total amount was added dropwise, the mixture was left to stand for 1 hour, and then a membrane filter (T050A 090C, manufactured by Toyo Kagaku K.K. (アドバンテック Bao ocean Co., Ltd.) was used as a filter, followed by suction filtration.

The filtrate was dried under vacuum at 60 ℃ for 16 hours to obtain a methanol-insoluble fraction. Further, using a rotary evaporator, the bath temperature was set to 40 ℃, the degree of vacuum was gradually decreased from 390Torr which was set initially, and finally to 30Torr, and after the solvent was removed from the filtrate, the soluble component remaining in the eggplant-shaped flask was recovered as a methanol soluble component.

The mass of the methanol-insoluble component and the mass of the methanol-soluble component were each weighed, and the ratio (mass%) of the amount of the methanol-soluble component to the total amount (100 mass%) of the amount of the methanol-soluble component and the amount of the methanol-insoluble component (methanol-soluble component fraction) was calculated.

< 7. measurement of Yellow Index (YI) and 680nm transmittance

The methanol-insoluble components of the methacrylic resins obtained in the production examples and production comparative examples were dissolved in chloroform at a concentration of 20 w/v% (i.e., a solution prepared at a ratio such that 10g of the sample was dissolved in chloroform to prepare a 50mL solution) to prepare measurement samples. Transmittance was measured with an ultraviolet-visible spectrophotometer (UV-2500 PC, manufactured by Shimadzu corporation) at a measurement wavelength of 380 to 780nm and a slit width of 2nm in an absorption cell having an optical path length of 10cm at a viewing angle of 10 degrees using an auxiliary light source C and chloroform as a reference.

YI (yellow index) was calculated by the following formula using XYZ color system in accordance with JIS K7373.

YI＝100(1.2769X-1.0592Z)/Y

Further, the transmittance (%) at a wavelength of 680nm was recorded under the same conditions as those for the above YI measurement.

< 8 evaluation of film formation of methacrylic resin film

Methacrylic resins obtained in production examples and comparative examples described later were dried with dehumidified air at 90 ℃ for 24 hours to reduce the moisture content to 300 mass ppm or less, and films were formed by the following method.

A film was produced by using a 15mm diameter biaxial extruder (manufactured by Kenon corporation, テクノベル) having a T-die with a width of 300mm provided at the tip of the extruder. As film forming conditions at this time, the temperature set at the tip of the extruder was 260 ℃, the T-die temperature was 255 ℃, the discharge rate was 1 kg/hour, and the temperature set at the chill roll was-10 ℃ to obtain a film having a film thickness of 80 μm. After continuously operating under these conditions for 6 hours, the film for evaluation was collected in a length of 1 m.

Then, using a roller after sufficiently cleaning before starting film formation, dirt on the roller surface was visually observed after 6 hours. The case where the film was hardly changed from before film formation and very small portions were slightly contaminated was evaluated as "o"; the slight contamination of the entire roll surface was evaluated as "Δ"; the case where the entire roller surface was contaminated and re-cleaning was required was evaluated as "X".

< 9. measurement of color tone of molded sheet >

(9-1) measurement of YI and Total light transmittance under the condition that the optical Path Length is 3mm

Molded pieces obtained in examples and comparative examples described below were sandwiched between a spectrocolorimeter (SD-5000, manufactured by Nippon Denshoku industries Co., Ltd.) so that a light source passed through the molded pieces in the thickness direction, and the YI (JIS K7373 standard) and the total light transmittance (JIS K7361-1 standard) were measured in a field of view of 10 ℃ under the condition of an optical path length of 3mm using a D65 light source. Measurements were performed 3 times, and the average value was used.

(9-2) measurement of YI and Y values under the condition that the optical Path Length is 80mm

Molded pieces obtained in examples and comparative examples to be described later were cut into 80mm pieces in the longitudinal direction, and both end faces perpendicular to the longitudinal direction of the molded pieces were polished with a grinder (product of メガロテクニカ, incorporated by Meijialo scientific Co., Ltd., Plabeauty (プラビューティー)) at a feed speed of 1 m/min at a rotation speed of 8500 rpm.

The polished molded piece was set so that the polished end face was perpendicular to the light source using a color difference meter (COH 300A, manufactured by Nippon Denshoku industries Co., Ltd.), and YI having an optical path length of 80mm and a Y value as an index of visual transmittance were measured in a field of view of 2 ℃ under a C light source.

[ raw materials ]

The raw materials used in the following production examples and production comparative examples are as follows.

[ [ monomer ] ]

Methyl methacrylate: asahi Kabushiki Kaisha

N-phenylmaleimide (phMI): manufactured by Nippon catalytic Co Ltd

N-cyclohexylmaleimide (chMI): manufactured by Nippon catalytic Co Ltd

Styrene: manufactured by Asahi Kasei Chemicals Ltd (Asahi Kasei ケミカルズ Co., Ltd.)

Methyl 2- (hydroxymethyl) acrylate (MHMA): manufactured by Combei Bloks, Inc

[ [ polymerization initiator ] ]

1, 1-bis (tert-butylperoxy) cyclohexane: perhexa C (パーヘキサ C) manufactured by Nichisu oil Co., Ltd "

1, 1-bis (tert-hexyl peroxide) cyclohexane: perhexa HC (パーヘキサ HC) manufactured by Nissan oil Co., Ltd "

T-butyl peroxyisopropyl monocarbonate: "perbutyl I (パーブチル I) manufactured by Nichioil Co., Ltd."

Tert-amyl peroxyisononanoate: LUPEROX570(ルぺロックス 570) manufactured by AkhimaGilfu K.K. (Arkema Yoshitomi, アルケマ Kyoki Co., Ltd.) "

Tert-butyl peroxy-2-ethylhexanoate: "perbutyl O (パーブチル O) manufactured by Nichisu oil Co., Ltd."

[ [ chain transfer agent ] ]

N-octyl mercaptan: kao corporation products

N-dodecyl mercaptan: kao corporation products

Production example 1 production of methacrylic resin (A) having N-substituted maleimide structural Unit

146.0kg of methyl methacrylate (hereinafter, MMA), 14.6kg of N-phenylmaleimide (hereinafter, phMI), 22.0kg of N-cyclohexylmaleimide (hereinafter, chMI), 0.174kg of N-octylmercaptan as a chain transfer agent, and 147.0kg of m-xylene (hereinafter, mXy) were measured, and added to 1.25m of a jacket-equipped temperature control device and a stirring blade³Stirring the mixture in the reactor to obtain a mixed monomer solution.

Then, 271.2kg of MMA, 27.1kg of phMI, 40.9kg of chMI, and 273.0kg of mXy were measured and charged into tank 1 to stir, thereby obtaining a mixed monomer solution for additional addition.

Further, 58.0kg of MMA were metered into the tank 2.

The content liquid in the reactor was bubbled with nitrogen at a rate of 30L/min for 1 hour, and the tanks 1 and 2 were bubbled with nitrogen at a rate of 10L/min for 30 minutes, respectively, to remove dissolved oxygen.

Then, the polymerization was started by blowing steam into the jacket body to raise the temperature of the solution in the reactor to 124 ℃ and adding a polymerization initiator solution obtained by dissolving 0.348kg of 1, 1-bis (t-butylperoxy) cyclohexane in mXy 4.652kg at a rate of 2 kg/hour with stirring at 50 rpm.

In the polymerization, the temperature of the solution in the reactor was controlled to 124. + -. 2 ℃ by temperature control based on the jacket. 30 minutes after the start of the polymerization, the rate of addition of the initiator solution was decreased to 1 kg/hr, and a mixed monomer solution for additional addition was added from tank 1 at a rate of 306.1 kg/hr for 2 hours.

Then, 2 hours and 45 minutes after the start of the polymerization, the total amount of MMA was added from tank 2 at a rate of 116 kg/hour for 30 minutes.

Further, the addition rate of the initiator solution was decreased to 0.5 kg/hr 3.5 hours after the start of the polymerization, to 0.25 kg/hr 4.5 hours after the start of the polymerization, to 0.125 kg/hr 6 hours after the start of the polymerization, and the addition was stopped 7 hours after the start of the polymerization.

After 10 hours from the start of the polymerization, a polymerization solution containing a methacrylic resin having a ring structure in its main chain was obtained.

The 1 hour half-life temperature of 1, 1-bis (t-butylperoxy) cyclohexane used as the initiator was 111 ℃, the 1 minute half-life temperature was 154 ℃, and the half-life at the polymerization temperature of 124 ℃ was 16 minutes.

After 4 hours, 6 hours, 8 hours, and 10 hours (at the end of polymerization), the polymer solutions were sampled and the polymerization conversion was analyzed according to the residual monomer concentration, and as a result, the polymer solutions were 84.8% after 4 hours, 93.3% after 6 hours, 95.7% after 8 hours, and 96.0% after 10 hours.

The polymerization solution was fed to a concentration apparatus comprising a tubular heat exchanger and a vaporization tank heated to 170 ℃ in advance, and the concentration of the polymer contained in the solution was increased to 70% by mass.

The resulting polymerization solution was supplied to a heat transfer area of 0.2m²The thin film evaporator of (3) for devolatilization.

The internal temperature of the apparatus was 280 ℃ and the pressure of the polymer after devolatilization was increased by a gear pump under the conditions of a supply amount of 30L/hr, a rotation number of 400rpm and a degree of vacuum of 30Torr, and the polymer was extruded from a die, water-cooled and pelletized to obtain a methacrylic resin (A) having an N-substituted maleimide structural unit.

The compositions of the resulting granular polymers were confirmed, and the constitutional units derived from the MMA, phMI, and chMI monomers were 81.3 mass%, 7.9 mass%, and 10.8 mass%, respectively. The weight-average molecular weight was 141000, Mz/Mw was 1.54, and Mw/Mn was 1.94. Other physical properties are shown in Table 2.

Production example 2 production of methacrylic resin (B) having N-substituted maleimide structural Unit

176.2kg of MMA, 6.0kg of phMI, 10.3kg of chMI, 0.168kg of n-octyl mercaptan as a chain transfer agent, and 153.7kg of mXy were measured and added to 1.25m of a temperature control device equipped with a jacket and stirring blades³Stirring the mixture in a reactor to obtain a mixed monomer solution.

Then, 327.1kg of MMA, 11.2kg of phMI, 19.2kg of chMI, and 285.3kg of mXy were measured and charged into tank 1 and stirred to obtain a mixed monomer solution for additional addition.

Further, 11.0kg of styrene was measured in the tank 2. The content liquid in the reactor was bubbled with nitrogen at a rate of 30L/min for 1 hour, and the content liquid in each of the tanks 1 and 2 was bubbled with nitrogen at a rate of 10L/min for 30 minutes, to remove dissolved oxygen.

Then, steam was blown into the jacket body to raise the temperature of the solution in the reactor to 124 ℃ and a polymerization initiator solution prepared by dissolving 0.337kg of 1, 1-bis (t-hexyl peroxide) cyclohexane in mXy 4.663kg was added at a rate of 2 kg/hour with stirring at 50rpm to start polymerization.

In the polymerization, the temperature of the solution in the reactor was controlled to 124. + -. 2 ℃ by temperature control based on the jacket. 30 minutes after the start of the polymerization, the rate of addition of the initiator solution was decreased to 1 kg/hr, and 257.1 kg/hr of the additional monomer mixture solution was added from tank 1 for 2.5 hours.

Then, 3 hours and 30 minutes after the start of the polymerization, the total amount of styrene was added from the tank 2 at a rate of 44 kg/hour for 15 minutes.

The 1-hour half-life temperature of 1, 1-bis (t-hexyl peroxide) cyclohexane used as the initiator was 107 ℃, the 1-minute half-life temperature was 149 ℃, and the half-life at the polymerization temperature of 124 ℃ was 11 minutes.

After 4 hours, 6 hours, 8 hours, and 10 hours (at the end of polymerization), the polymer solutions were sampled, and the polymerization conversion was analyzed according to the residual monomer concentration, and as a result, the polymer solutions were 84.5% after 4 hours, 92.2% after 6 hours, 95.2% after 8 hours, and 95.5% after 10 hours.

The polymerization solution was fed to a concentration apparatus comprising a tubular heat exchanger and a vaporization tank heated to 170 ℃ in advance, and the concentration of the polymer contained in the solution was increased to 70% by mass. The resulting polymerization solution was supplied to a heat transfer area of 0.2m²The thin film evaporator of (3) for devolatilization.

The internal temperature of the apparatus was 280 ℃ and the pressure of the polymer after devolatilization was increased by a gear pump under the conditions of a supply amount of 30L/hr, a rotation number of 400rpm and a degree of vacuum of 30Torr, and the polymer was extruded from a die, water-cooled and pelletized to obtain a methacrylic resin (B) having an N-substituted maleimide structural unit.

The compositions of the resulting granular polymers were confirmed to be 89.8 mass%, 3.5 mass%, 5.1 mass%, and 1.6 mass%, respectively, of the constitutional units derived from the MMA, phMI, chMI, and styrene monomers. The weight-average molecular weight was 133000, Mz/Mw was 1.58 and Mw/Mn was 2.07. Other physical properties are shown in Table 2.

Production example 3 production of methacrylic resin (C) having N-substituted maleimide structural Unit

500kg of MMA, 39.6kg of phMI, 10.4kg of chMI, 0.275kg of n-octylmercaptan as a chain transfer agent, and 450kg of mXy were measured and added to 1.25m of a jacket-equipped temperature control device and a stirring blade³Stirring the mixture in a reactor to obtain a mixed monomer solution.

The content liquid in the reactor was bubbled with nitrogen at a rate of 30L/min for 1 hour to remove dissolved oxygen. Then, the polymerization was started by blowing steam into the jacket body to raise the temperature of the solution in the reactor to 120 ℃ and adding a polymerization initiator solution obtained by dissolving 0.175kg of 1, 1-bis (t-butylperoxy) cyclohexane in mXy 3.000.000 kg at a rate of 1.5 kg/hour with stirring at 50 rpm.

In the polymerization, the temperature of the solution in the reactor was controlled to 120. + -. 2 ℃ by temperature regulation based on the jacket. 30 minutes after the start of the polymerization, the rate of addition of the initiator solution was decreased to 0.75 kg/hr, 2 hours after the start of the polymerization, the rate of addition was decreased to 0.5 kg/hr, 3 hours after the start of the polymerization, the rate of addition was decreased to 0.2 kg/hr, and 7 hours after the start of the polymerization, the addition was stopped.

The 1-hour half-life temperature of 1, 1-bis (t-butylperoxy) cyclohexane used as the initiator was 111 ℃, the 1-minute half-life temperature was 154 ℃, and the half-life at the polymerization temperature of 120 ℃ was 24 minutes.

The polymer solution was sampled 5 hours after the start of the polymerization, 8 hours after the start of the polymerization, and 10 hours after the end of the polymerization (at the end of the polymerization), and the polymerization conversion was analyzed based on the residual monomer concentration, and as a result, the sampling was 85.0% after 5 hours, 93.3% after 8 hours, and 94.0% after 10 hours.

The internal temperature of the apparatus was 280 ℃ and the pressure of the polymer after devolatilization was increased by a gear pump under the conditions of a supply amount of 30L/hr, a rotation number of 400rpm and a degree of vacuum of 30Torr, and the polymer was extruded from a die, water-cooled and pelletized to obtain a methacrylic resin (C) having an N-substituted maleimide structural unit.

The compositions of the resulting granular polymers were confirmed to be 91.1 mass%, 7.3 mass%, and 1.6 mass%, respectively, of the constitutional units derived from the MMA, phMI, and chMI monomers. The weight-average molecular weight was 151000, Mz/Mw was 1.75, and Mw/Mn was 2.29. Other physical properties are shown in Table 2.

Production example 4 production of methacrylic resin (D) having N-substituted maleimide structural Unit

112.5kg of MMA, 12.5kg of phMI, 0.50kg of n-octylmercaptan as a chain transfer agent, and 125kg of toluene were measured and added to 1.25m of a jacket-equipped temperature control device and a stirring blade³Stirring the mixture in a reactor to obtain a mixed monomer solution. Then, 337.5kg of MMA, 37.5kg of phMI, and 375kg of toluene were measured and added to tank 1, followed by stirring to obtain a mixed monomer solution for additional addition.

The content liquid in the reactor was bubbled with nitrogen at a rate of 30L/min for 1 hour, and the content liquid in the tank 1 was bubbled with nitrogen at a rate of 10L/min for 30 minutes, to remove dissolved oxygen.

Then, steam was blown into the jacket body to raise the temperature of the solution in the reactor to 110 ℃ and polymerization was started by adding a polymerization initiator solution obtained by dissolving 0.5kg of t-butyl peroxyisopropyl monocarbonate in 1kg of toluene while stirring at 50 rpm. Further, a polymerization initiator solution prepared by dissolving 0.75kg of t-butyl peroxyisopropyl monocarbonate in 1.5kg of toluene was added at a constant rate for 1 hour.

30 minutes after the start of the polymerization, the content liquid in tank 1 was added at a constant rate over 2 hours.

In the polymerization, the temperature of the solution in the reactor was controlled to 110. + -. 2 ℃ by temperature control based on the jacket. After 12 hours from the start of the polymerization, a polymerization solution containing a methacrylic resin having a ring structure in its main chain was obtained.

The 1-hour half-life temperature of t-butyl peroxyisopropyl monocarbonate used as the initiator was 118 ℃, and the half-life thereof was 153 minutes at a polymerization temperature of 110 ℃. After 5.5 hours, 7 hours, 10 hours, and 12 hours (at the end of polymerization), the polymer solutions were sampled and the polymerization conversion was analyzed according to the residual monomer concentration, and as a result, 84.2% after 5.5 hours, 90.0% after 7 hours, 95% after 10 hours, and 97.3% after 12 hours were obtained.

The resulting polymerization solution was supplied to a heat transfer area of 0.2m²The thin film evaporator of (3) for devolatilization. The internal temperature of the apparatus was 280 ℃ and the pressure of the polymer after devolatilization was increased by a gear pump under the conditions of a supply amount of 30L/hr, a rotation number of 400rpm and a degree of vacuum of 30Torr, and the polymer was extruded from a die, water-cooled and pelletized to obtain a methacrylic resin (D) having an N-substituted maleimide structural unit.

The compositions of the resulting granular polymers were confirmed, and the constitutional units derived from the MMA and phMI monomers were 90.1 mass% and 9.9 mass%, respectively. The weight-average molecular weight was 145000, Mz/Mw was 1.65, and Mw/Mn was 2.16. Other physical properties are shown in Table 2.

Production example 5 production of methacrylic resin (E) having lactone Ring Structure Unit

To an autoclave equipped with a stirrer, a temperature sensor, a cooling tube and a nitrogen gas inlet tube, which had been previously purged with nitrogen, were added 20 parts by mass of methyl methacrylate, 5 parts by mass of methyl 2- (hydroxymethyl) acrylate, 25 parts by mass of toluene and 0.025 parts by mass of tris (2, 4-di-t-butylphenyl) phosphite as an organophosphorus compound.

Then, while introducing nitrogen gas, the temperature was raised to 100 ℃ and 0.05 part by mass of tert-amyl peroxyisononanoate was added as a polymerization initiator, and at the same time, 0.075 part by mass of a toluene solution containing tert-amyl peroxyisononanoate was added dropwise, and while dropwise adding this solution over 1.5 hours, solution polymerization was carried out under reflux conditions at about 105 to 110 ℃, and further, polymerization was continued for 5.5 hours. Further, 30 minutes after the start of the polymerization, 20 parts by mass of methyl methacrylate, 5 parts by mass of methyl 2- (hydroxymethyl) acrylate, and 25 parts by mass of toluene were added at a constant rate over 2 hours.

To the resulting polymer solution, 0.05 part by mass of a stearyl phosphate/distearyl phosphate mixture as an organic phosphorus compound was added as a cyclization catalyst, and a cyclization condensation reaction was carried out under reflux conditions at about 90to 102 ℃ for 2 hours.

The t-amyl peroxyisononanoate used as an initiator had a 1-hour half-life temperature of 114 ℃, a half-life of 101 minutes at a polymerization temperature of 110 ℃ and a half-life of 180 minutes at 105 ℃. The polymer solutions were sampled 4 hours after the start of the polymerization and 7.5 hours after the start of the polymerization, and the polymerization conversion was analyzed based on the residual monomer concentration, and as a result, the polymer solutions were 84.6% after 4 hours and 94.8% after 7.5 hours. The average time value of the polymerization temperature from 0 hour to 7.5 hours after the start of the polymerization was 105 ℃.

The resulting polymer solution was then heated to 240 ℃ by a heater consisting of a multitubular heat exchanger, and introduced into a twin-screw extruder equipped with a plurality of exhaust ports for devolatilization and a plurality of sub-feed ports located downstream, to perform a cyclization reaction while devolatilizing.

The obtained copolymer solution was supplied to the twin-screw extruder in terms of resin to 15 kg/hr, and conditions of a cylinder temperature of 250 ℃, a rotation number of 100rpm, and a degree of vacuum of 10to 300Torr were set.

The resin composition melt-kneaded by the twin-screw extruder was extruded from a die, water-cooled, and pelletized to obtain a resin composition.

The composition of the obtained resin composition was confirmed, and as a result, the content of the lactone ring structural unit was 32.8 mass%. The content of the lactone ring structural unit is determined by the method described in Japanese patent application laid-open No. 2007-297620. The weight-average molecular weight of the obtained resin composition was 124000, Mz/Mw was 1.62 and Mw/Mn was 2.13. Other physical properties are shown in Table 2.

Production comparative example 1 production of methacrylic resin (F) having N-substituted maleimide structural Unit

445.5kg of MMA, 44.0kg of phMI, 60.5kg of chMI, 0.55kg of n-octylmercaptan as a chain transfer agent, and 450kg of mXy were measured and added to 1.25m of a temperature control device provided with a jacket and stirring blades³Stirring the mixture in a reactor to obtain a mixed monomer solution.

The content liquid in the reactor was bubbled with nitrogen at a rate of 30L/min for 1 hour to remove dissolved oxygen. Then, steam was blown into the jacket body to raise the temperature of the solution in the reactor to 130 ℃ and 1 kg/hr of a polymerization initiator solution prepared by dissolving 1.10kg of t-butyl peroxy-2-ethylhexanoate in mXy 4.9.9 kg of t-butyl peroxy-2-ethylhexanoate was added for 6 hours while stirring at 50rpm, thereby starting the polymerization.

In the polymerization, the temperature of the solution in the reactor was controlled to 130. + -. 2 ℃ by temperature control based on the jacket. After 8 hours from the start of the polymerization, a polymerization solution containing a methacrylic resin having a ring structure in its main chain was obtained. The t-butyl peroxy-2-ethylhexanoate used as the initiator had a half-life temperature of 92 ℃ in 1 hour, a half-life temperature of 134 ℃ in 1 minute, and a half-life of 1.4 minutes at a polymerization temperature of 130 ℃. The polymer solutions were sampled 3.3 hours after the start of the polymerization, 6 hours after the start of the polymerization, and 8 hours after the end of the polymerization (at the end of the polymerization), and the polymerization conversion was analyzed based on the residual monomer concentration, and as a result, the sampling was 84.9% after 3.3 hours, 96.7% after 6 hours, and 96.8% after 8 hours.

The polymerization solution was fed to a concentration apparatus comprising a tubular heat exchanger and a vaporization tank heated to 170 ℃ in advance, and the concentration of the polymer contained in the solution was increased to 70% by mass. The resulting polymerization solution was supplied to a heat transfer area of 0.2m²The thin film evaporator of (3) for devolatilization. The internal temperature of the apparatus was 280 ℃ and the pressure of the polymer after devolatilization was increased by a gear pump under the conditions of a supply amount of 30L/hr, a rotation number of 400rpm and a degree of vacuum of 30Torr, and the polymer was extruded from a die, water-cooled and pelletized to obtain a methacrylic resin (F) having an N-substituted maleimide structural unit.

The compositions of the resulting granular polymers were confirmed to be 81.3 mass%, 7.7 mass%, and 11 mass%, respectively, of the constitutional units derived from the MMA, phMI, and chMI monomers. The weight-average molecular weight was 143000, Mz/Mw was 1.85, and Mw/Mn was 2.75. Other physical properties are shown in Table 2.

Production comparative example 2 production of methacrylic resin (G) having N-substituted maleimide structural Unit

450.0kg of MMA, 50.0kg of phMI, 0.50kg of n-dodecylmercaptan as a chain transfer agent, and 500kg of toluene were measured and added to 1.25m of a jacket-equipped temperature control device and a stirring blade³Stirring the mixture in a reactor to obtain a mixed monomer solution.

The content liquid in the reactor was bubbled with nitrogen at a rate of 30L/min for 1 hour to remove dissolved oxygen. Then, steam was blown into the jacket body to raise the temperature of the solution in the reactor to 110 ℃ and polymerization was started by adding a polymerization initiator solution in which 1.50kg of t-butyl peroxyisopropyl monocarbonate was dissolved in 4.5kg of toluene into the reactor while stirring at 50 rpm.

The 1-hour half-life temperature of t-butyl peroxyisopropyl monocarbonate used as the initiator was 118 ℃, and the half-life thereof was 153 minutes at a polymerization temperature of 110 ℃.

After 4 hours, 8 hours, and 12 hours (at the end of polymerization), the polymer solutions were sampled, and the polymerization conversion was analyzed according to the residual monomer concentration, and as a result, the polymer solutions were 90.4% after 4 hours, 96.5% after 8 hours, and 98.0% after 12 hours.

The resulting polymerization solution was supplied to a heat transfer area of 0.2m²The thin film evaporator of (3) for devolatilization. The internal temperature of the apparatus was 280 ℃ and the pressure of the polymer after devolatilization was increased by a gear pump under the conditions of a supply amount of 30L/hr, a rotation number of 400rpm and a degree of vacuum of 30Torr, and the polymer was extruded from a die, water-cooled and pelletized to obtain a methacrylic resin (G) having an N-substituted maleimide structural unit.

The compositions of the resulting granular polymers were confirmed, and the constitutional units derived from the MMA and phMI monomers were 90.3 mass% and 9.7 mass%, respectively. The weight-average molecular weight was 155000, Mz/Mw was 1.82, and Mw/Mn was 2.63. Other physical properties are shown in Table 2.

Production comparative example 3 production of methacrylic resin (H) having N-substituted maleimide structural Unit

Metering of MMA 140.0kg and chMI 1000kg of toluene and 250kg of toluene, and was added to 1.25m of a jacket-equipped temperature control device and a stirring blade³Stirring the mixture in the reactor to obtain a mixed monomer solution.

Then, 82.5kg of MMA, 25.0kg of chMI, 35.0kg of styrene and 200.0kg of toluene were measured, and the resulting mixture was put into tank 1 and stirred to obtain a monomer mixture solution for additional addition.

Further, 82.5kg of MMA, 35.0kg of styrene and 50.0kg of toluene were measured and charged into tank 2, followed by stirring to obtain a mixed monomer solution for additional addition.

The content liquid in the reactor was bubbled with nitrogen at a rate of 30L/min for 1 hour, and the content liquid in each of the tank 1 and the tank 2 was bubbled with nitrogen at a rate of 10L/min for 30 minutes, thereby removing dissolved oxygen.

Then, steam was blown into the jacket body to raise the temperature of the solution in the reactor to 110 ℃ and polymerization was started by adding a polymerization initiator solution, in which 0.20kg of t-butyl peroxyisopropyl monocarbonate was dissolved in 0.8kg of toluene, to the reactor while stirring at 50rpm, and 2 kg/hr of a polymerization initiator solution, in which 2.30kg of t-butyl peroxyisopropyl monocarbonate was dissolved in 4.70kg of toluene, was added for 3.5 hours.

Further, the content liquid in tank 1 was added at a constant rate for 3.5 hours after the start of the polymerization, and the content liquid in tank 2 was added at a constant rate for the following 3.5 hours.

In the polymerization, the temperature of the solution in the reactor was controlled to 110. + -. 2 ℃ by temperature control based on the jacket. After 10 hours from the start of the polymerization, a polymerization solution containing a methacrylic resin having a ring structure in its main chain was obtained.

After 7 hours and 10 hours from the start of the polymerization (at the end of the polymerization), the polymer solutions were sampled, and the polymerization conversion was analyzed based on the residual monomer concentration, whereby the polymer solution was 90.1% after 7 hours and 97.3% after 10 hours.

The resulting polymerization solution was supplied to a heat transfer area of 0.2m²The thin film evaporator of (3) for devolatilization. The internal temperature of the apparatus was 280 ℃ and the pressure of the polymer after devolatilization was increased by a gear pump under the conditions of a supply amount of 30L/hr, a rotation number of 400rpm and a degree of vacuum of 30Torr, and the polymer was extruded from a die, water-cooled and pelletized to obtain a methacrylic resin (H) having an N-substituted maleimide structural unit.

The compositions of the resulting granular polymers were confirmed, and the constitutional units derived from MMA, chMI, and styrene monomers were 60.3 mass%, 25.5 mass%, and 14.2 mass%, respectively. The weight-average molecular weight was 102000, Mz/Mw was 1.90, and Mw/Mn was 2.84. Other physical properties are shown in Table 2.

Production comparative example 4 production of methacrylic resin (I) having lactone Ring Structure Unit

To an autoclave equipped with a stirrer, a temperature sensor, a cooling tube and a nitrogen gas inlet tube, which had been previously purged with nitrogen, were added 40 parts by mass of methyl methacrylate, 10 parts by mass of methyl 2- (hydroxymethyl) acrylate, 50 parts by mass of toluene and 0.025 parts by mass of tris (2, 4-di-t-butylphenyl) phosphite as an organophosphorus compound.

Then, while introducing nitrogen gas, the temperature was raised to 100 ℃ and 0.05 part by mass of tert-amyl peroxyisononanoate was added as a polymerization initiator, and at the same time, dropwise addition of a toluene solution containing 0.1 part by mass of tert-amyl peroxyisononanoate was started, and while dropwise addition of the solution was performed over 2 hours, solution polymerization was performed under reflux conditions at about 105 to 110 ℃, and further, polymerization was continued for 4 hours.

The t-amyl peroxyisononanoate used as an initiator had a 1-hour half-life temperature of 114 ℃, a half-life of 101 minutes at a polymerization temperature of 110 ℃ and a half-life of 180 minutes at 105 ℃.

The polymer solution was sampled 4 hours and 6 hours after the start of the polymerization, and the polymerization conversion was analyzed according to the residual monomer concentration, and as a result, the polymer solution was 89.8% after 4 hours and 95.2% after 6 hours.

The resulting polymer solution was heated to 240 ℃ by a heater comprising a multitubular heat exchanger, and introduced into a twin-screw extruder equipped with a plurality of exhaust ports for devolatilization and a plurality of sub-feed ports located downstream, thereby carrying out the cyclization reaction while carrying out devolatilization.

The composition of the obtained resin composition was confirmed, and as a result, the content of the lactone ring structural unit was 31.5 mass%. The content of the lactone ring structural unit is determined by the method described in Japanese patent application laid-open No. 2007-297620. Further, the weight average molecular weight of the obtained resin composition was 121000, Mz/Mw was 1.78 and Mw/Mn was 2.52. Other physical properties are shown in Table 2.

TABLE 2

(remarks) resin composition

PHC: 1, 1-bis (t-butylperoxy) cyclohexane

PHHC: 1, 1-di (tert-hexyl peroxide) cyclohexane

PBI: peroxyisopropyl tert-butyl monocarbonate

L570: peroxyisononanoic acid tert-amyl ester

PBO: peroxy-2-ethylhexanoic acid tert-butyl ester

Examples 1 to 5 and comparative examples 1 to 4

Using the methacrylic resins (A) to (I) obtained in production examples 1 to 5 and production comparative examples 1 to 4, long and thin molded pieces having a thickness of 3mm × 12mm × 124mm were produced by an injection molding machine (AUTO SHOT C Series MODEL 15A, manufactured by FANUC corporation) under conditions of a molding temperature of 250 ℃ and a mold temperature of 90 ℃.

< 9. measurement of color tone of molded sheet >

The thus-obtained molded piece was sandwiched so that the light source passed through the molded piece in the thickness direction thereof using a spectrocolorimeter (SD-5000, manufactured by Nippon Denshoku industries Co., Ltd.), and the YI (JIS K7373 standard) and the total light transmittance (JIS K7361-1 standard) (%) under the condition of an optical path length of 3mm were measured in a field of view of 10 ℃ from a D65 light source. Measurements were performed 3 times, and the average value was used.

The obtained molded piece was cut into 80mm pieces in the longitudinal direction, and both end faces perpendicular to the longitudinal direction of the molded piece were polished with a grinder (product of Mill technologies, メガロテクニカ, Ltd., Plabeauty (プラビューティー)) at a feed speed of 1 m/min at a rotation number of 8500rpm of the cutter.

The color tone of each molded piece was measured. The measured values obtained are shown in table 3.

TABLE 3

The methacrylic resin molded article of the present embodiment has a low YI under a long light path condition, is excellent in color tone, and has a high transmittance, and therefore, the molded article can be preferably used for optical member applications such as a light guide plate, and automotive member applications such as a tail lamp, an instrument cover, and a headlamp.

The methacrylic resin molded product of the present invention has high heat resistance, highly controlled birefringence, and excellent color tone and transparency.

The methacrylic resin molded product of the present invention can be preferably used for the following applications: for example, as the optical material, a light guide plate, a diffusion plate, a polarizing plate protective film used in displays such as a liquid crystal display, a plasma display, an organic EL display, a field emission display, a rear projection television, and the like; 1/4 wavelength plate, 1/2 wavelength plate, etc. phase difference plate; liquid crystal optical compensation films such as a viewing angle control film; a display front panel; a display substrate; a lens; transparent conductive substrates such as transparent substrates and touch panels used in solar cells; a coating material for a waveguide, a lens array, an optical fiber, and an optical fiber in the fields of an optical communication system, an optical exchange system, and an optical measurement system, or in an optical product such as a head mount display and a liquid crystal projector; lenses, lens covers, etc. of LEDs, and further, household goods, OA equipment, AV equipment, battery electronic equipment, lighting equipment; automotive member applications such as tail lamps, instrument covers, headlamps, light guide bars, lenses, and front panels for car navigation; shell applications; replacing sanitary ware and the like.

Claims

1. A methacrylic resin molded body which is characterized by being composed of a methacrylic resin or a composition containing the methacrylic resin,

the methacrylic resin comprises a structural unit B having a ring structure in the main chain, the structural unit B containing at least one structural unit selected from the group consisting of an N-substituted maleimide structural unit B-1 and a lactone ring structural unit B-2,

the yellowness index YI obtained by measuring the methanol-insoluble component in a 20 w/v% chloroform solution using an absorption cell having an optical path length of 10cm is 0to 7.

2. The molded methacrylic resin body according to claim 1, wherein a transmittance at 680nm as measured with a 20 w/v% chloroform solution of the methanol-insoluble component using an absorption cell having an optical path length of 10cm is 90% or more.

3. The molded methacrylic resin according to claim 1, wherein the methacrylic resin contains 50 to 97% by mass of the methacrylate monomer units A, based on 100% by mass of the methacrylic resin.

4. The molded methacrylic resin according to claim 2, wherein the methacrylic resin contains 50 to 97% by mass of the methacrylate monomer units A, based on 100% by mass of the methacrylic resin.

5. The methacrylic resin molded body according to any one of claims 1 to 4, wherein the methacrylic resin contains 3 to 30 mass% of the structural unit B having a ring structure in its main chain and 0to 20 mass% of another vinyl monomer unit C copolymerizable with a methacrylate ester monomer, based on 100 mass% of the methacrylic resin.

6. The molded methacrylic resin body according to claim 5, wherein the content of the structural unit B is 45 to 100% by mass when the total amount of the structural unit B and the monomer unit C is 100% by mass.

7. The molded methacrylic resin body according to claim 5, wherein the monomer unit C contains at least one structural unit selected from the group consisting of an acrylate monomer, an aromatic vinyl monomer and a vinyl cyanide monomer.

8. The molded methacrylic resin body according to claim 6, wherein the monomer unit C contains at least one structural unit selected from the group consisting of an acrylate monomer, an aromatic vinyl monomer and a vinyl cyanide monomer.

9. The methacrylic resin molded body according to any one of claims 1 to 4 and 6 to 8, wherein the photoelastic coefficient of the methacrylic resin is-2 x 10^-12～+2×10^-12Pa^-1。

10. The methacrylic resin molded article according to claim 5, wherein the photoelastic coefficient of the methacrylic resin is-2X 10^-12～+2×10^-12Pa^-1。

11. The methacrylic resin molded body according to any one of claims 1 to 4, 6 to 8, and 10, wherein a ratio Mz/Mw of a Z-average molecular weight Mz to a weight-average molecular weight Mw, which is measured by gel permeation chromatography GPC on the methacrylic resin, is 1.3 to 2.0.

12. The molded methacrylic resin according to claim 5, wherein a ratio Mz/Mw of a Z-average molecular weight Mz to a weight-average molecular weight Mw, which is obtained by measuring the methacrylic resin by gel permeation chromatography GPC, is 1.3 to 2.0.

13. The molded methacrylic resin according to claim 9, wherein a ratio Mz/Mw of a Z-average molecular weight Mz to a weight-average molecular weight Mw, which is obtained by measuring the methacrylic resin by gel permeation chromatography GPC, is 1.3 to 2.0.

14. An optical member or an automotive member, characterized by being composed of the methacrylic resin molded body according to any one of claims 1 to 13.